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TRANSCRIPT
I
PREPARED FOR THE BRITISH COLUMBIA HYDRO AND POWER
AUTHORITY, VANCOUVER 1, BRITISH, COLUMBIA
UNITED ST ATES DEPARTMENT OF THE INTERIOR
BUREAU OF RECLAMATION
HYDRAULIC MODEL STUDIES OF PORTAGE MOUNTAIN
DEVELOPMENT LOW-LEVEL OUTLET WORKS
BRITISH COLUMBIA, CANADA
Hydraulics Branch Report No. Hyd-562
DIVISION OF RESEARCH
OFFICE OF CHIEF ENGINEER DENVER, COLORADO
June 30, 1966
The information contained in this report may not be used in any publication, advertising, or other promotion in such a manner as to constitute an endorsement by the United States Government or the Bureau of Reclamation, either explicit or implicit, of any material, product, device, or process that may be referred to in the report.
IN REPLY
UNITED STATES DEPARTMENT OF THE INTERIOR
BUREAU OF RECLAMATION
OFFICE OF CHIEF ENGINEER
REFER TO: D-293 BUILDING 53, DENVER FEDERAL CENTER
DENVER. COLORADO 80225
June 30, 1966
General Manager International Power and Engineering
Consultants, Ltd. 570 Dunsmuir Vancouver 2, British Columbia Canada
Sir:
I am pleased to submit Hydraulics Branch Report No. Hyd-562 which constitutes our final report on studies conducted on the low-level outlet works of Portage Mountain Dam. I believe you will find this report interesting and informative, and that it will satisfy the requirements of your office for a comprehensive discussion of the extensive test program.
Enclosure
Very truly yours,
:a. P. Bellport Chief Engineer
CONTENTS
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Concl11Sions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 The Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 The Investigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Irltroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Preliminary Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Discharge capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Flow characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Air demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Second Design 7
New design requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Flow characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Tailwater requirements . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Third Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Flow characteristics and tailwater requirements . . . . 8 Air demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Fourth Design g
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Flow characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Tailwater depth requirements . . . . . . . . . . . . . . . . . . . . . 9 Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Air demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Other Design Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . 11
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CONTENTS- -Continued
Page
Final Model Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Flow characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Tail water requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Water surface profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Final design operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Air demand . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 One-valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Discharge capacity .......................... ·. . . . . . . . . 18
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Table
Dimensions of Hydraulic Features . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
British Columbia--Key Plan .............. : ................ . Powerplant General Arrangement .......................... . Low-level Outlet General Arrangement ..................... . 1: 14 Sc ale Model ......................................... . Preliminary Design ....................................... . Computed Water Surface ................................... . Preliminary Discharge Capacity Curves--Two 84-inch,
Fixed-cone Valves ...................................... . Preliminary Design--Two-valve Operation--100 Percent
Open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preliminary Design--Two-valve Operation--50 Percent
Open--5, 000 cfs--Reservoir Elevation 1900 ................ . Preliminary Design--Two-valve Operation--100 Percent
Open--8, 600 cfs--Reservoir Elevation 2000 ................ . Preliminary Desian--Reservoir Elevation 2125 .............. . Air Demand--Preliminary Design .......................... . Baffle Pier Arrangement--Second Design .................... . Tailwater Requirements--Second Design .................... . Baffle Pier Arrangement- -Fourth Design .................... . Tailwater Requirements ................................... . Upstream Baffle Pier Piezometers and Pressures ............ . Downstream Baffle Pier Piezometers and Pressures ......... .
ii
Figure
1 2
4 5 6
7
8
9
10 11 12 13 14 15 16 17 18
CONTENTS--Continued
Figure
Dynamic Pressures on Baffle Piers . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Upstream Baffle Pier Pressure Fluctuations--10, 300 cfs--
Valves Fully Open . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Air Demand--Fourth and Final Designs . . . . . . . . . . . . . . . . . . . . . . . 21 Proposed Dokan Fillet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Operation with Dokan Fillet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Flow Energy at Station 13+67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Operation with Ring Deflector and Baffle Removed . . . . . . . . . . . . . 25 Tailwater Requirements for Hydraulic Jump--Final Design . . . . . 26 Water Surface Profiles through the Lined Section . . . . . . . . . . . . . . 27 Final Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Final Design--Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Final Design--Discharge through the Lined Section. . . . . . . . . . . . . 30 Final Design--Discharge through the Barrel Liner . . . . . . . . . . . . . 31 Final Design--Discharge through the Barrel Liner . . . . . . . . . . . . . 32 Final Design--Reservoir Elevation 2125--Discharge 5, 000 cfs. . . 33 Liner Wall--Piezometers and Pressures.. . . . . . . . . . . . . . . . . . . . . 34 Ring Deflector--Piezometers and Pressures . . . . . . . . . . . . . . . . . . 35 Dynamic Pressures in Barrel Liner and Deflector Ring . . . . . . . . 36 Barrel Liner--Piezometer Locations . . . . . . . . . . . . . . . . . . . . . . . . . 37 Simultaneous Dynamic Pressures--Valves Fully Open--
Reservoir Elevation 2125 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Simultaneous Dynamic Pressures--Valves Fully Open--
Reservoir Elevation 2225 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Proposed Modifications to Ring Deflector . . . . . . . . . . . . . . . . . . . . . 40 Final Design--Reservoir Elevation 2125--One-valve
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Discharge and Head Loss Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Discharge Capacity Curves--Two 84-inch Fixed-cone Valves.... 43
iii
ABSTRACT
Studies on a 1:14 scale model of the low level outlet works of Portage Mountain Development show the fixed-cone valve-ring deflector combination provides a relatively simple and effective device for flow control and energy dissipation. The ring deflector contributes significantly to energy dissipation. Baffle piers downstream from the deflector and a weir at the downstream turtnel portal can be added later to improve energy dissipation if necessary. The extent of the steel-lined section required downstream of the valves was determined. High fluctuating pressures were measured on the wall of the liner in the impingement area of the jet and on the upstream face of the ring deflector at the crown and invert. Pressures on the lip of the deflector were slightly subatmospheric. No uniform simultaneous peaking of pressures at widely separated areas occurred on the deflector ring. A recirculating air supply tunnel was developed to provide near atmospheric pressures within the cone-shaped jet as well as upstream of the jet at the valves. Nonsymmetrical operation of the valves is not recommended. The design discharge of 10, 000 cfs per tunnel at reservoir elevation 2125 was verified by the model operation.
DESCRIPTORS-- *outlet works/ diversion tunnels/ conduits/ tunnel plugs/ hydraulic structures/ *hydraulic models/ hydraulic jumps/ stilling basins/ *air demand/ head losses/ discharge measurement/ energy losses/ backwater profiles/ steel linings/ weir crests/ baffles/ vapor pressures/ cavitation/ *energy dissipation/ water surface/ erosion/ tunnel linings/ osclllographs/ transducers/ laboratory tests IDENTIFIERS-- *jet flow gates/ tunnel transitions/ fixed-cone valves/ ring deflectors/ subatmosoheric oressures/ Portage Mtn Dvlpmt, Can/ bell-mouthed entrances/ British Columbia, Canada
V
UNITED STATES DEPARTMENT OF THE INTERIOR
BUREAU OF RECLAMATION
Office of Chief Engineer Division of Research Hydraulics Branch Structures and Equipment
Section Denver, Colorado June 30, 1966
Laboratory Report No. Hyd-562 Written by: G. L. Beichley Checked by: T. J. Rhone Reviewed by: W. E. Wagner Submitted by: H. M. Martin
HYDRAULIC MODEL STUDIES OF PORTAGE MOUNTAIN DEVELOPMENT LOW-LEVEL OUTLET WORKS
BRITISH COLUMBIA, CANADA
PURPOSE
This study was undertaken to develop a satisfactory method of dissipating the energy of the high-velocity flow in the low-level outlet works, and to determine the hydraulic flow characteristics of the structure.
CONCLUSIONS
1. In the preliminary design hydraulic jumps formed in the baffled area and in the tunnel for discharges obtained at reservoir elevations up to 2000. Above reservoir elevation 2000 the jump in the baffled area swept out and shooting flow with large turbulent boils or waves was present, Figures 10 and 11.
2. Additional baffle piers improved the energy dissipation, but did not force a hydraulic jump in the baffled area. A 14-foot-high weir at the downstream tunnel portal was necessary to provide sufficient tailwater to retain a hydraulic jump in the baffled area, Figure 14.
3. A 43-foot-diameter barrel replacing the preliminary 40-footdiameter barrel and an off-center position for the air inlet made no significant changes in the energy dissipation or air demand. However, a slight instability or flutter in the jet emerging from the deflector ring was noticed. Reducing the height of the ring deflector from 6 to 4-1/2 feet stabilized the jet and slightly increased the air demand.
4. A 15-foot-high weir at the portal provided sufficient tailwater for a good hydraulic jump and smooth flow conditions with the larger barrel, smaller deflector, and with the number of baffle piers reduced from 15 to 8.
INTRODUCTION
Portage Mountain damsite is located in the Peace River Canyon in northern British Columbia 480 miles north of Vancouver and 80 miles west of Dawson Creek. The nearest community is Hudson Hope, approximately 11 air miles from the site. The nearest center of communication is Fort St. John, approximately 55 air miles east of the site. The map of the catchment area (Figure 1) shows some of the above-mentioned geographical locations.
The general arrangement of the development is shown in Figure 2. The zoned earthfill dam has a 6, 700-foot-long crest at elevation 2230 and rises 600 feet above the riverbed. A radial gate controlled spillway is located on the right abutment. An underground powerplant is in the left abutment upstream of the diversion tunnel outlets. Diversion of the Peace River during construction of the dam will be effected by means of three 48-foot-diameter horseshoe-shaped concrete-lined tunnels located in the right abutment. Ultimately, the diversion tunnels will be plugged and two will be converted to serve as low-level outlets during and after the reservoir filling period. The third tunnel will serve for access to the remaining two by means of transverse tunnel connections, Figure 3.
The low-level outlets will be placed in the tunnel plugs and are designed to control the reservoir level and to provide minimum flows in the Peace River during the initial reservoir filling; after completion of the dam their function will be reduced to standby duty as emergency outlets.
The diversion works include the intake approach channel; the three 48-foot-diameter, concrete-lined, horseshoe-shaped diversion tunnels together with their intakes; outlet transitions; and outlet channels, as shown in Figure 3. The intake approach channel, located in the right bank of the river about 1, 800 feet upstream from the axis of the dam, is divided into three separate channels by shoulders of rock left in situ.
THE MODELS
Two models were used in the study. The first was built to develop an outlet works using jet-flow gates for flow control; and the second was used for the development ofan outlet scheme utilizing fixed-cone valves (Howell-Bunger type). Fixed-cone valves were adopted for the prototype installation and the development of an adequate energy dissipator is the subject of this report. The scheme utilizing the jet-flow gates is discussed briefly in the appendix.
The model for the fixed-cone valve scheme (Figure 4) was a 1: 14 scale reproduction of a portion of Diversion Tunnel 2 from the tunnel plug to
3
a point 472 feet downstream of the plug. The model included about 58 percent of the true length of the 84-inch outlet conduits through the tunnel plug. The bellmouth entrances were studied and found to be satisfactory in the initial model, and were not rebuilt for the second model but were represented by cone-shaped transitions. The shortened tunnels and cone-shaped transitions were provided to insure that the head at the valves would equal or exceed the equivalent prototype head. The two Howell-Bunger valves were constructed from brass; one valve was available in the laboratory and the second was built from the same plans. These valves had four vanes supporting the center dispersion cone. Information received near the end of the studies revealed that the prototype valves would probably have six vanes. It is believed that this difference will cause only minor variations in the flow pattern.
The model was initially operated with air supplied directly from the atmosphere through a 12-foot-diameter air inlet located in the tunnel directly above the valves. However, before any extensive air demand measurements were made, the complete 12-foot-diameter recirculating air tunnel was installed as shown in Figure 4. Three different sized circular orifices were used in the air tunnel to measure the air demand.
Flow was supplied to the model by means of the laboratory's permanent pumping system; discharges were measured by calibrated Venturi meters permanently installed in the laboratory supply system. The operating head {or reservoir elevation) was measured one tunnel diameter upstream from the plug by means of a differential mercury manometer. Flow depths in the downstream tunnel were controlled by an adjustable tailgate at the downstream end of the model tunnel and were measured by a staff gage at Station 13+67, approximately 401 feet downstream from the tunnel plug.
THE INVESTIGATION
Introduction
The investigation was primarily concerned with dissipating the energy in the flow from the outlet works control valves. Studies of the flow characteristics in the bellmouthed conduit entrances were conducted in the model of the jet-flow gates (see Appendix).
Principally, the studies were conducted with both valves discharging simultaneously at maximum capacity of approximately 5, 000 and 5, 500 cfs each at reservoir elevations 2125 and 2225. However, investigations were also made with partial valve openings for flows as low as 2, 500 cfs per valve at reservoir elevation 2125, and with fully open valves operating at all reservoir elevations ranging from 1, 700 to 2, 200 feet. Singlevalve operation was also studied.
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Tests on the 1: 24 scale model using the jet-flow gate control had indicated that an extensive stilling basin would be necessary to effectively dissipate the flow energy, or that a major portion of the diversion tunnel should be reinforced with a thicker concrete lining. Therefore, the jet-flow gates were abandoned and a second scheme utilizing fixed-cone (Howell-Bunger type) valves with a ring deflector similar to the design for the Oroville Dam outlet worksY was adopted. This arrangement permitted energy dissipation to be effected in a relatively short distance between the valves and a ring deflector in a st-eel-lined barrel section.
Preliminary Design
Description. --Two 84-inch fixed-cone valves discharged into the diversion tunnel from two 84-inch-diameter conduits that passed through the tunnel plug. The conduits were 3. 5 feet above centerline of the diversion tunnel and were spaced 19 feet apart. A 40-foot-diameter reinforced concrete barrel lined with steel plate extended for a distance of 63 feet downstream from the tunnel plug, Figure 5. The lower half o~ the liner extended downstream for an additional 31 feet, and a quarter segment on the invert another 65 feet.
A 4. 5-foot-high ring deflector was located 42 feet downstream from the tunnel plug and two rows of five baffle blocks each were located 80 and 145 feet downstream from the plug. The baffle blocks extended to a height of 11. 5 feet above the tunnel invert.
Operating conditions. --The tests were made under the following operating conditions:
Tail water conditions
Curve A (Figure 6)
Curve B (Figure 6)
Reservoir elevations
1690-1770 1770-2000
2000-2125 1690-1770 1770-2000
Valve opening
Fully open only Fully open down to
2, 500 cfs/valve Fully open to close Fully open only Fully open down to
2, 500 cfs/valve
Curve A represented completed project conditions when the invert at the tunnel outlet portal, elevation 1640, controlled the upstream tailwater level. Since only a portion of the tunnel was reproduced in the
1J"Hydraulic Model Studies of the River Outlet Works at Oroville Dam -California Department of Water Resources - State of California, " Report No. Hyd-508, D,. Colgate.
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model, stage-discharge relationships (backwater curves) in the tunnel upstream to Station 13+67 were computed for this type of control, Figure 6. Backwater curves obtained from the computations indicated that the slope of the tunnel was supercritical and a hydraulic jump would form downstream from the 40-foot-diameter liner. Therefore, Curve A provided a shooting flow tailwater condition downstream from the liner.
Curve B represented high tailwater conditions estimated to exist in the river during a temporary construction phase when the river channel was partially blocked. The tailwater elevation at Station 13+67 in the tunnel was assumed to be level with that in the river channel for this condition, Figure 6.
Discharge capacity. --For the initial model operation~ the discharge capacity of the valves was determined for 25-, 50-, ·, 5-, and 100-percent gate openings and related to the reservoir elevation measured in the model tunnel upstream of the tunnel plug, Figure 7. These capacities were expected to be slightly greater than would occur in the prototype since all of the head loss was not represented in the model. In the initial studies, 10, 300 cfs was discharged at reservoir elevation 2125 with the gates fully open. In the final capacity tests, with the computed operating head measured 1 diameter upstream of the valves, the discharge proved to be 10, 000 cfs.
Flow characteristics. --For tailwater Curve A, Figure 6, two hydraulic jumps occurred in the tunnel downstream from the deflector ring for all test discharges obtained at reservoir elevations up to 2000, Figures 8, 9, and 10. One jump occurred in the baffled area in the 40-foot-diameter liner and the other in the 48-foot-diameter horseshoe tunnel.
At reservoir elevation 2125 with the valves fully open, discharging about 10, 300 cfs, the jump occurred only in the tunnel. The jump in the baffled area swept out and a large boil or surge occurred over each of the two sets of five baffle piers, Figure 11. Similar conditions occurred with the valves 50 percent open and discharging approximately 7, 100 cfs at reservoir elevation 2125.
For tailwater Curve B, Figure 6, a hydraulic jump formed in the baffled area of the 40-foot liner and tranquil flow existed in the downstream tunnel with the valves fully open and reservoir elevations 1690 to 1770, and for flows of 5, 000 to 8, 600 cfs at various valve openings and reservoir elevations ranging from 1770 to 2000 feet. The energy dissipation was quite satisfactory, Figures 8, 9, and 10. It was not anticipated that the outlet works would discharge at reservoir elevations above 2000 with Curve B tailwater; therefore, higher reservoir elevations were not tested in the model.
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Air demand. --The air demand at the valves in the 40-foot-diameter barrel liner was measured initially with air supplied directly from outside the tunnel, and later with the air supplied through a recirculating tunnel as previously described. No significant differences in the quantity of airflow could be detected from either source of supply.
A maximum air velocity of 300 feet per second is normally used as a design criterion to keep below the "whistling" range. The head differential required to create an air velocity of 300 feet per second is about 1. 5 feet of water. Assuming an entrance, line, and exit head loss in the air duct of 0. 5 foot, a maximum subatmospheric pressure of 2 feet of water was permissible in the tunnel around the valves. The air demand was approximately 7, 000 cfs for valve openings of 50-, 7 5-, and 100-percent when the pressures at the valves was about 2 feet of water below atmospheric, Figure 12. Tailwater elevation did not affect the air demand unless the tail water was extremely high, such as tailwater elevation 1675, and then only a very negligible amount.
Based on a maximum air demand of 7,000 cfs, a 6-foot-diameter flatbottom horseshoe tunnel would provide sufficient area for a velocity of about 220 feet per second. Since the accurate prediction of prototype air demand by the use of scaled models has not been proven, it was desirable to provide a sufficiently large tunnel to maintain the air velocity well below the "whistling" velocity of 300 feet per second. Therefore, a 10-foot-diameter flat-bottom horseshoe tunnel was chosen which provided a theoretical velocity of less than 80 feet per second when the airflow was 7,000 cfs.
The inlet to the recirculating air tunnel appeared to be sufficiently far downstream to prevent splash and spray at the baffle blocks from entering the air tunnel or interfering with the intake of air.
A curtain wall extending from the water surface to the crown of the tunnel was installed at the downstream end of the model to simulate a prototype curtain at the portal that might be used to prevent extremely cold outside air from entering the tunnel. This curtain slightly reduced the air demand.
Second Design
New design requirements. --At this stage of the investigation, the design criteria were modified such that the outlet works might be required to operate with the valves fully open at reservoir elevation 2225, or 100 feet higher than originally specified. In addition, tailwater Curve Bin Figure 6 was eliminated as an operating condition.
Description. --Twenty-four different arrangements of the baffle piers and ring deflector were tested in arriving at the arrangement of the
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second design shown in Figure 13. The design was essentially the same as the preliminary design except that five additional baffle piers were installed and the baffle piers in the upstream row were rearranged.
Flow characteristics. --At reservoir elevations 2125 and 2225 with the valves fully open, this arrangement provided considerable energy dissipation with a minimum amount of splash and high boils for the Curve A tailwater operating conditions. However, the additional blocks failed to create a hydraulic jump and shooting flow existed in the baffled area.
Tailwater requirements. --Tests were made to determine the tailwater depth required at Station 13+67 to bring the toe of the hydraulic jump to three locations in the tunnel: (1) the downstream side of the downstream row of baffles; (2) just upstream of the downstream row of baffles; and (3) at the downstream end of the half liner, Figure 14. These tests were conducted with gate openings of 35-, 50-, 7 5-, and 100-percent for a range of reservoir elevations from 1690 to 2225.
Computations based on these tailwater tests indicated that a 14-foothigh, unobstructed weir at the tunnel portal, with its crest at elevation 1654, would provide sufficient tailwater depth to maintain the toe of the jump upstream of the downstream row of baffles, Figure 14.
Third Design
Description. --The diameter of the barrel liner at the downstream end of the plug was increased from 40 to 43 feet for structural reasons. The elevation and spacing of the fixed-cone valves were not changed. The cross-sectional height of the ring deflector was increased from 4. 5 to 6 feet, while maintaining the inside diameter at 31 feet. The upstream toe of the ring deflector was located at the same station as in the preliminary design. The number, height, and location of the baffles were not altered.
The 12-foot-diameter air vent with its inlet at the same tunnel station, was rotated to a position 45° to the right of the tunnel crown, and terminated in an 8- by 10-foot rectangular duct tangent to the tunnel crown at the valve chamber.
Flow characteristics and tailwater depth requirements. --There was no significant difference in energy dissipation or tailwater depth requirements from those observed in the second design. The principal difference in the flow conditions was a slight instability or flutter of the flow emerging from the ring deflector.
Air demand. --Neither the larger barrel liner nor the relocation of the air tunnel inlet caused significant change in air demand over the preliminary design.
8
Fourth Design
Description. --Approximately 18 modifications to the third design, including different arrangements of baffle piers, ring deflector size and location, and valve spacing, were tested in arriving at the fourth design. As a result of these tests and other design considerations, four major changes were adopted, as follows, Figure 15:
a. A 15-foot-high weir (not shown in Figure 15) was proposed at the downstream tunnel portal.
b. The number of baffle piers was reduced from 15 to 8.
c. The cross-sectional height of the ring deflector was reduced from 6 to 4. 5 feet, thereby increasing the inside diameter of the ring from 31 to 34 feet.
d. The spacing between the valves was increased from 19 to 21. 5 feet for structural reasons: the elevation was not changed.
e. The air vent supply tunnel was relocated to a position directly above the tunnel crown.
Flow characteristics. --The deeper tailwater provided by the 15-foothigh weir at the portal, Figure 16, maintained the hydraulic jump in the baffled area and eliminated the need for the large number of baffle piers that were required in previous arrangements. However, eight baffle piers, five in the downstream row and three in the upstream row, were still used primarily to stabilize the hydraulic jump. The hydraulic jump was a little farther downstream with the fewer number of baffle piers. However, a good hydraulic jump formed in the baffled area with a fairly smooth water surface in the downstream tunnel, particularly with the valves discharging fully open at reservoir elevation 2125. Discharges at reservoir elevation 2225 caused considerable turbulence, but the operation was believed to be satisfactory for this infrequent operating condition.
The reduction in the height of the ring deflector improved the stability of the jet and reduced the flutter, and small spurts of water from the jet only occasionally splashed against the walls of the tunnel. However, due to the smaller obstruction offered by the deflector, the hydraulic jump formed a little farther downstream in the tunnel.
Tailwater depth requirements. --Tailwater elevations necessary to maintain the hydraulic jump at three different locations in the baffled area were determined from the model, for 50-, 75-, and 100-percent valve openings. Tailwater elevations were determined {1) with the toe of the hydraulic jump just upstream of the downstream row of five baffles,
9
( 2·) with the toe of the jump near the upstream end of the upstream baffles, and (3) with the toe of the jump near the 43-foot-diameter barrel.
The tail water depth required to maintain the jump at the first location was the minimum to prevent a jump from forming downstream from the baffled area; any tailwater elevation that equaled or exceeded this minimum requirement provided satisfactory flow conditions in the baffled area and in the downstream tunnel. Tailwater depths required to place the jump at the second location were pre-f erred, inasmuch as these depths provided a large margin of safety that would permit these depths to be reduced, or exceeded, by approximately 3 or 4 feet and still hold the jump in the baffled area. The pool that formed beneath the valves never submerged the valves with the jump at any of the three locations.
Water surface fluctuations at Station 13+67 in the tunnel were recorded for the minimum tailwater elevations, Figure 16. The maximum fluctuation from peak to trough was approximately 4. 5 feet with the valves fully open at reservoir elevation 2225. The amplitude of the fluctuation for any specific discharge did not vary noticeably with tailwater depth.
Pressures. --Pressures on the baffle piers were recorded for the design tailwater, assuming the use of the proposed 15-foot weir, and for no tailwater, assuming no weir at the portal and no hydraulic jump in the baffled area.
Piezometer locations and water manometer pressures are shown in Figures 17 and 18. Neither tailwater elevation nor discharge had any significant effect on the pressures observed on the upstream baffle when the valves were discharging at reservoir elevation 2125 or greater, Figure 17. However, on the sides and top of the downstream baffle the pressures were lower with no tail water than with the design tail water. Lower pressures also were observed for either tailwater condition when the reservoir was increased from elevation 2125 to 2225.
The lowest pressures on the upstream baffle occurred near the elliptical upstream corners on the baffle 5. 7 5 feet above the floor. The lowest pressures on the downstream baffle were also observed at the elliptical corners but were near the bottom of the baffle. The lowest observed pressures were about 8 feet of water below atmospheric on both upstream and downstream baffles.
A representative group of the more critical pressures that indicated low subatmospheric, high impact, or large fluctuations in pressure were further evaluated using pressure transducers and a direct writing oscillograph. The dynamic pressures interpreted from these oscillograph
10
recordings are tabulated in Figure 19 and some are plotted in Figure 20 for comparison with the water manometer pressures.
The maximum and minimum dynamic pressures recorded in Figure 19 were chosen so that the pressure was within these limits at least 95 percent of the time. For example, Figure 20 shows that the dynamic pressure at Piezometer No. 10 fluctuates from 5 feet of water above atmospheric to 17 feet below atmospheric, or a range of 22 feet, as compared to a range of about 2 feet as measured by the water manometer. Extreme maximum and minimum pressures were also recorded to show the extremes to which the dynamic pressures occasionally fluctuated, Fig-ures 19 and 20. The extreme fluctuations for Piezometer No. 10 were from 30 feet of water above atmospheric to vapor pressure. The frequency of dynamic pressure fluctuations and the number of these fluctuations that reached or exceeded the maximum and minimum pressure limits, including hesitations and minor reversals in the pressure trace, were recorded, Figure 19. Only a small percent of the fluctuations reached or exceeded the limits; for example, at Piezometer No. 10, for a discharge of 10, 300 cfs with either high or low tailwater, the average number of fluctuations was 8 per second while the average number that reached or exceeded the maximum and minimum limits was 1. 2 per second. Pressures that reached the vapor pressure at any piezometer occurred less than 1 percent of the operating time.
Air demand. - -The smaller ring deflector approximately doubled the subatmospheric pressure in the valve chamber, which increased the air demand. However, for a chamber pressure of 2 feet of water,
' below atmospheric, the maximum air demand only increased from about 7, 000 cfs to about 9, 000 cfs. At 100- and 50-percent valve openings, the air demand increased to approximately 8, 000 cf s, Figure 21.
The larger air demand increased the computed velocity in the 10-foot horseshoe tunnel from about 80 to 100 feet per second, which is still well below the 300 feet per second limit recommended for design purposes.
Other Design Modifications
Tests were also made with the valves raised 14. 7 5 inches to 4. 73 feet above the tunnel centerline and, at the same time, with the valve spacing reduced from 21. 5 to 19. 48 feet. This arrangement provided a more stable jet emerging from the ring deflector and a good hydraulic jump. (This arrangement was tested prior to increasing the inside diameter of the ring deflector; subsequent tests indicated that the larger inside diameter ring deflector also stabilized the jet, making it unnecessary to raise the valves.) Tailwater depths under the valves were greater with the valves in the higher position. Air demand was slightly more than in the third design but slightly less than in the fourth design.
11
Cone-shaped fillets placed under the valves, Figures 22 and 23, similar to those used at Dakan Dam in Iraq, proved to be of no value. The fillets increased the instability of the jet emerging from the ring deflector, particularly when used with the smaller inside diameter ring deflector. The fillets prevented the pool of water from forming under the valves, and appeared to increase the force of the jet striking the lower half of the ring deflector, causing the jet leaving the ring to spurt intermittently upward and impinge on the crown of the tunnel. Since the ring deflector prevented the formation of a pool of water that might submerge the valves at high tailwater, fillets for this purpose at Portage Mountain were unnecessary. The air demand was not significantly changed by the fillets.
Final Model Design
General. --A review of the operating history of the project indicated that the prototype tunnels had discharged river diversion flow at velocities up to 55 feet per second with no apparent damage to the original tunnel lining. It was conceivable that the baffle piers and portal weir of Design 4 could be eliminated in the final design if velocities in the outlet works flows did not exceed this value. Therefore, tests were made to determine the flow characteristics without the baffle piers or ring deflector. From these tests it was concluded that the fixed-cone valve-ring deflector combination without baffle piers provided a relatively simple and effective low-level outlet device for flow control and energy dissipation. Under the maximum gross head at Portage Mountain Dam, and with full open valves discharging about 11, 000 cfs per tunnel, the energy would be dissipated approximately as follows:
In tunnel and conduits upstream of valves . . From valves to a point 100 feet downstream
of ring deflector. . . . . . . . . . . . . In low energy jump in tunnel . . . . . . . .
Assuming a 25-foot flow depth in the tunnel, the total remaining energy would be about 27 feet.
. 120 feet
. . . 390 feet . 15 feet
525 feet
Flow characteristics. --Flow depths were measured, and the velocity and energy in the flow computed at Station 13+67 assuming no weir control at the downstream portal. The measurements were made with and without the baffles and also with and without the ring deflector, Figure 24.
With the baffles and ring deflector removed, and operating with the valves 100-percent open at reservoir elevation 2125, the portion of
12
the jet emerging from the crown of the barrel liner followed a trajectory which reached the invert about 200 feet downstream of the valves, i.e., beneath the air-circulating tunnel inlet, Figure 25. From this point the extremely turbulent flow shot downstream at a velocity estimated at over 70 feet per second, or considerably higher than the velocities realized during the diversion flows (accurate measurement of the model water depth and velocity was difficult because of the turbulence and :fluctuating water surface). The total energy head at this velocity and flow depth exceeds 80 feet and the jump would be swept from the tunnel. This test showed conclusively that the ring deflactor was essential to intercept the jet flowing along the walls of the barrel liner, to deflect it inward on itself, and to direct it downward toward the tunnel invert.
With the baffles removed and the ring deflector in place the velocity downstream was only 45 feet per second for valves fully open discharging 11,300 cfs. The corresponding energy head was about 39 feet, as compared to the gross head of 550 feet. Under these conditions, a low energy jump, with downstream depth about 25 feet, formed in the tunnel.
With all eight baffles in place in addition to the ring deflector, the velocity was reduced to approximately 38 feet per second for both valves fully open discharging 11,300 cfs. The total energy head was about 32 feet as compared to 39 feet with the baffles removed.
As a result of these tests it was concluded that the ring deflector was essential in reducing the velocity and energy in the flow but that the baffles did not significantly increase the energy dissipation. It was also concluded that formation of the hydraulic jump in the steellined section was not necessary and therefore, the 15-foot-high weir at the tunnel portal could be omitted. However, after the reservoir filling perio~ the tunnel inverts should be inspected for damage and the need for portal weirs and baffle piers should be reassessed at that time.
Tailwater requirements. --The tests, as discussed above, showed that the baffle piers and portal weirs were unnecessary for satisfactory energy dissipation, and that a low-energy jump will form in the downstream tunnel. However, should tunnel damage occur as the result of the low-energy jump, a weir crest at the tunnel portal could be installed to provide sufficient tailwater to move the jump location to the lined section. The tailwater depth at Station 13+67 required to accomplish this without the addition of baffles is shown in Figure 26 for two different jump locations. If at that time it is also decided to use eight baffles arranged as shown in Figure 15, the tailwater depth requirements are shown in Figure 16.
13
Water surface profiles. --Water surface profiles through the lined section downstream from the ring deflector were obtained for 11, 000 cfs to determine the necessary length and height of the 43-foot-diameter liner, Figure 27. The tests showed that the 65-foot-long quarter liner along the invert should be replaced with a 52-foot-long liner in the lower half of the tunnel.
A long sloping fillet diverging from the end of the 43-foot-diameter half liner to the 48-foot-diameter horseshoe tunnel was considered but not tested. The velocity of the downstream end of the liner was estimated to be 40 feet per second; it was believed that adverse pressures would be more likely to occur with a fillet than with the offset at the end of the liner. Abrasion damage at the offset is not likely since debris is not expected to be present in the flow. It is important that all foreign material be removed from the tunnel before the outlets are placed in operation.
Final Design Operation
The final design evolved from this series of tests resulted in a simple and effective energy dissipating system consisting of the 4. 5-foot-high ring deflector in the 43-foot-diameter barrel liner and an 83-foot-long semicircular extension of the liner along the invert downstream from the deflector, Figures 28 and 29; the baffle piers and portal weir were eliminated.
Flow conditions in this structure were satisfactory over the full range of discharges and reservoir elevations, Figures 30 to 33.
Pressures. - -Pressures on the walls of the barrel liner, and on the ring deflector were recorded during operation with full open valves discharging 10, 300 and 11, 500 cfs. Data were obtained first by means of water manometers, Figures 34 and 35. Piezometers No. 2 and 3 in the liner were located in the impingement area of the jet from the left valve. Piezometer No. 1 located immediately upstream of the impingement area, and Piezometers No. 4, 5, and 6 were on the downstream side. Piezometer No. 7 was located in an impingement area of a fin of water caused by one of the structural ribs on the valve cone.
The geometry of the impingement areas and to some extent the magnitude of the pressures were not truly represented in the model, inasmuch as there were only four structural ribs in the model valves as compared to six in the prototype. However, the piezometers were located in areas of maximum impact pressures, and the maximum recorded pressures can be used as a guide for prototype design purposes.
14
The pressure at Piezometer No. 2 for the two discharges averaged approximately 133 and 161 feet of water, respectively, and fluctuated tremendously as discussed later. The pressure at Piezometer No. 3 was about 90 feet less than at No. 2 and the pressure at Piezometer No. 7 was much less than at either of these two, Figure 34. Just upstream from the impingement area at Piezometer No. 1 and downstream at Piezometers No. 4, 5, and 6, pressures were near atmospheric.
Pressures on the upstream side of the ring deflector were highest near the base of the deflector at the crown and invert of the barrel liner, Figure 35, and fluctuated considerably. At Piezometer No. 1 (nearest the crown) the average pressures were approximately 112 feet and 86 feet of water for discharges of 11, 500 and 10, 300 cfs, respectively.
The average pressure at Piezometer No. 15, near the upstream edge of the horizontal lip of the ring deflector on the invert, was slightly below atmospheric and fluctuated to as much as 7 feet of water below atmospheric at 11, 500 cfs. Pressures on the downstream side of the ring deflector were atmospheric or above.
A representative group of the more critical pressure readings that indicated low subatmospheric, high impact, or large fluctuations in pressure on the ring deflector and walls of the liner were further evaluated using pressure transducers and a direct writing oscillograph. The dynamic pressures interpreted from these oscillograph recordings are tabulated in Figure 36.
The dynamic maximum and minimum pressures tabulated in Figure 36 were not exceeded more than 5 percent of the time. Extreme maximum and minimum pressures are also tabulated to show the extremes to which the dynamic pressures occasionally fluctuated. It is believed that the maximum and minimum limits chosen are conservative.
For comparison of the dynamic pressure fluctuation with the water manometer pressure fluctuation the following two examples are cited: at Piezometer No. 15 on the lip of the ring deflector at the tunnel invert, the dynamic pressure fluctuated from about 22 feet of water below atmospheric to 14 feet above, with extremes as low as vapor pressure and as high as 44 feet above atmospheric; the water manometer measurement had shown fluctuations from atmospheric pressure to 7 feet below atmospheric. At Piezometer No. 2 in the jet impingement area on the wall liner, the dynamic pressure fluctuation ranged from 28 feet of water to approximately 378 feet of water above atmospheric for 11, 500 cfs with extremes from 30 feet below atmospheric to 476 feet above atmospheric compared to a maximum water manometer fluctuation of about 70 feet of water. This wide
15
fluctuation in pressure at Piezometer No. 2 possibly is due in part to a quiver or movement in the location of the impingement area of the jet on the model walls. The reason for the quiver is not known.
The frequency of the dynamic pressure fluctuations, and the frequency at which these fluctuations reached or exceeded the maximumandminimum dynamic pressure limits, including hesitations and minor reversals in the pressure trace, are tabulated in Figure 36. Only a small percentage of the fluctuations reached or exceeded the limits. For example, at Piezometer No. 2 in the jet impingement area on the wall, the average number of fluctuations per second was about 15 and the average number reaching either limit ranged from 0. 9 to 3. 2 for discharges of 10, 300 and 11, 500 cfs.
The high-frequency dynamic pressure vibrations could easily be felt on the 1/ 4-inch-thick plastic wall of the model barrel liner upstream of the ring deflector. A much lower frequency vibration could be seen and felt on any part of the model tunnel downstream from the ring deflector. Dynamic pressures were recorded simultaneously at eight piezometers shown in Figure 37 to determine if simultaneous peaking of the pressures occurred. Six of the piezometers were at two dif.-f erent cross section locations in the ring deflector; the seventh was a probe extending through the wall of the barrel liner into the interior of the hollow cone-shaped jet; and the eighth piezometer was located in the wall of the barrel liner upstream of the jet. The latter two piezometers measured the ambient pressure in the hollow portion of the cone jet and in the valve chamber rather than waterflow pressure.
These simultaneous recordings were obtained for discharges with the valves fully open for reservoir elevations 1800, 1900, 2000, 2125, and 2225. There appeared to be no uniform simultaneous peaking of the pressures, except for some uniformity noted at adjacent piezometers in the same cross section of the ring deflector. Oscillograph recordings obtained during operation at reservoir elevations 2125 and 2225 are shown on Figures 38 and 39.
It was noted that the average pressure at Piezometer No. 15, located on the horizontal lip of the ring deflector at the invert, was near atmo spheric but that at reservoir elevation 1900 to elevation 2125, the dynamic pressure fluctuated sometimes to vapor pressure. This was also true in previous test data discussed above and recorded in Figure 36. This was due to a fluctuating submergence of the piezometer by the backwater pool under the jet from the ring deflector, which was greatest at reservoir elevations 1900 to 2000. At reservoir elevations 1800 and 2225 the piezometer was open to the atmosphere nearly 100 percent of the time.
16
To prevent these low, fluctuating pressures, the top surface of the ring deflector should be redesigned to provide a sharp edge as shown in the alternate designs in Figure 40. Although these proposed modifications were not tested, the square corner and offset will prevent the jet from clinging to the top surface of the ring deflector.
The recording charts of Figures 38 and 39 do not show the rapid frequency of pressure fluctuations which existed at Piezometers No. 20, 21, and 22 located on the ring deflector near the horizontal centerline. This was due to the extra long copper leads between these piezometers and the transducers attenuating the pressure fluctuations.
Reference is made to Harrold' s papery in which he cited the Corps of Engineers as having concluded from model and prototype comparison tests that vapor pressure existing 25 percent of the operating time could be tolerated for infrequent operation. At Piezometers No. 2, 14, and 15, Figure 36, pressures as low as the vapor pressure occurred only about 1 percent of the operating time.
Air demand. --Air demand was the same as that required for the fourth design, Figure 21.
Further observations were made using a pressure probe to the interior of the jet and the wall piezometer in the valve chamber. The dynamic pressure measurements disclosed that the pressure within the jet and in the valve chamber upstream of the jet were nearly identical, Figures 38 and 39. Pressure measurements were also made in the interior of the jet near the valves, about halfway between the valves and deflector ring, and just upstream from the deflector ring. The pressures of these three points were nearly identical, indicating that the interiors of the jets were well aerated.
One valve operation. --Flow appearance with one valve open and the other closed was unsatisfactory. The jet from the ring deflector impinged upon the side of the tunnel opposite the operating valve in an area extending partly above the top of the half liner, Figure 41. The flow oscillated from side to side throughout the tunnel, and the toe of the jump was on a diagonal line across the tunnel because of the nonuniform flow distribution.
Complete aeration of the downstream side of the ring deflector lip at about 35° up from the invert was not evident. However, pressure measurements at this point on the lip of the ring deflector showed the pressure to be atmospheric for one valve discharging at all reservoir
YHarrold, J. C., "Experience of the Corps of Engineers, 11 Transactions of the American Society of Civil Engineers, Paper No. 2225, Vol. 112, 1947.
17
elevations. The recommended alternate modifications of the ring deflector lip (Figure 40) should provide adequate aeration of the downstream side of the ring deflector. Nonsymmetrical operation of the valves is not recommended, except for emergency releases.
Discharge capacity. --To verify the expected prototype capacities the discharge measurements were related to the total head (measured pressure head plus computed velocity head)., observed one valve diameter upstream of the valves, Figure 42. Computed head losses from the reservoir to this point.are also shown in Figure 42. A friction factor of 0. 0096 for new smooth butt-welded pipe3/ was assumed in computing the friction loss in the tunnel plug conduits, and an entrance loss of 0. 10 velocity head in the pipe was assumed at the bellmouth entrance to the conduits. This total head loss plus the measured pressure head and the computed velocity head provides the anticipated capacity curves shown in Figure 43. These computations and the model verified that approximately 10, 000 cfs will be discharged from two fully open valves at reservoir elevation 2125. At reservoir elevation 2225 the full open gates will discharge approximately 11, 100 cfs.
3/Engineering Monograph No. 7, "Friction Factors for Large Conduits Flowing Full, " U.S. Department of the Interior, Bureau of Reclamation.
18
Table 1
DIMENSIONS OF HYDRAULIC FEATURES
l"eature
Height of dam
Length of dam at crest
Diversion tunnel length (approximate)
Diversion tunnel length downstream from tunnel plug (approximate)
Diversion tunnel diameter
Tunnel plug length
Fixed-cone valve diameter
Outlet works design capacity
English units
600 feet
6, 7UO feet
2, 700 feet
1, 600 feet
48 feet
200 feet
84 inches
10, 000 cubic feet per second per tunnel
Nietrk uni ts
183. 00 meters
2, 042. 00 meters
823. 00 meters
488. 00 meters
14. 63 meters
60. 96 meters
2. 13 meters
283. 2 cubic meters per second per tunnel
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control chamber
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l"ORTAGIE MOUNTAIN IXYIELOl"MIIN1'
LOW LEVEL OUTLETS GENERAL ARRANGEMENT
M c..,
Looking downstream
PORT AGE MOUNTAIN DEVELOPMENT WW LEVEL OUTLET WORKS
1:14 SCALE MODEL
!:d t-rj (1) .....
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FIGURE 5 REPORT HY0-~62
693
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, El. 1669. 96 -~ - El . 16 4 4.95 '- --s =0 ,0 0 9 5 ~
~-- ------- ---------___..__,--J-'
SECTION ON <i.
PORTAGE MOUNTAIN DEVELOP MENT LOW LEV EL OUTLET WORKS
PR EL I MINARY DE SIG N
I : 14 SCALE MODEL
693
FIGURE 6 REPORT HY0-562
io""" L -- --t O,OOOcfs
I --1655
I -----z - 7 - - -Critic al Depth Critical Depth -- ---" -~-" -, 0
l/_ -/_ I ' ' I', '
,1 --5,000 cfs I L - "
/ /: I \ \
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I J I - --2,500 cfs Hydrau lie Jump-- -- r-,....._ - --I I - r -- _ .... u
<t LL ,
I I -,_ _r Critical Depth- -__ ...,-
a:: ::) (/) 1645
a:: w ~
STAGE DISCHARG~ RELATIONSHIP FOR CURVE "A
<t :i:
ROUGHNESS COEFFICIENT " n" ASSUMED AT 0 .014 T. W. Gage a t Sta . 13+67 --
Invert EI. 1638 . 64 ----164 0
- ...... 1637.5
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z 0
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1670
~
1660
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-
STATIONING IN TUNNEL NO . 2
I I I I I I
Curve 8 -- --..... ~ ----- Water Surface Elevation
.' for critico I depth at Sta . 13 + 67
~ - ~
.-,, -- -./ ---- ' -Curve A ---.,. ,
NOTE
5 10 15 20 25 CURVE 8 - RIVER DISCHARGE IN 1000 CFS
CURVE A - TUNNEL DISCHA RGE IN 1000 CFS
CURVE A. TAILWATER IS ESTIMATED AT STA . 13+67 FROM WATER SURFACE PROFILES ABOVE .
CURVE B . TAILWATER IS ESTIMATED AT STA . 13+ 67 TO BE SAME AS IN RIVER CHANNEL AT PORTAL .
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS COMPUTED WATER SURFACE
I : 14 SCALE MODEL
-
30
Fl GU R E 7 RE P O R T HY0-562
2300
2200 r. ~ ) I
i I ~ ,
25%- 50% I I-w 2100 w IL
z
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J v/ v~ v~ PERCENT A GES REF ER
TO VALVE OPEN I NGS
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693
2 3 4 5 6 7 8
DISCHARGE I N 1000 c fs
9
NOTE : For final ca l ibr a ti on see Figures 42 and 43 t. of valve at El . 1669 . 96
PORTAGE MOUN T AIN DEVELOPMENT LOW LEVEL OUTLET WORKS
PR ELIMINARY DISCHARGE CAPACITY CURVES TWO 8 4 - INCH FIXED CONE VA LVES
I : 14 SCALE MODEL
10
J I
I
II 12
M -.J
T. W. El. 1645. 2 (Curve A) Q = 2, 000 cfs Reservoir El. 1690
T. W. El. 1662. 8 (Curve B) Q = 4, 300 cfs Reservoir El. 1 770
T. W. El. 1646. 5 (Curve A) Q = 4, 300 cfs Reservoir El. 1770
T. W. El. __ 1669. 0 (Cur.ve B aesuming total riverflow Q_ = 2?, 000 cfs) Q = 4, 300 cfs
Reservoir El. 1770
Note: T. W. Elevations are set at Station 13+67
PORTAGE MOUNTAlli DEVELOPMENT LOW LEVEL OUTLET WORKS
PRELlMINARY DESIGN--TWO-VALVE OPERATION 100 PERCENT OPEN 1:14 SCALE MODEL
!;d t-rj (D ,....
'g� � (D
z CXl
0
I C]l m NJ
Figure 9 Report No. Hyd-562
Note: T. W. elevations are set at Station 13+67
T. W. El. 1647. 0 (Curve A)
T. W. El. 1662. 8 (Curve B)
T. W. El. 1669. 0 (Curve B assuming total river discharge= 28,000 cfs)
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
PRELTh1INARY DESIGN--TWO-VALVE OPERATION 50 PERCENT OPEN 5, 000 CFS--RESERVOIR ELEVATION 1900
1:14 SCALE MODEL
28
T. W. El. 1649. 4 (Curve A)
T. W. El. 1664. 5 (Curve B)
T. W. El. 1669. 0 (Curve B assuming total river discharge= 28,000 cfs)
PORTAGE MOUNTArn DEVELOPMENT LOW LEVEL OUTLET WORKS
Figure 10 Report No. Hyd-562
Note: T. W. elevations are set at Station 13+67
PRELilvilNARY DESIGN--TWO-VALVE OPERATION 100 PERCENT OPEN 8,600 CFS--RESERVOIR ELEVATION 2000
1:14 SCALE MODEL
29
Figure 11 Report No. Hyd-562
- .. Note: T. W. eleva
tions are set at Station 13+67
Valves 100 percent open Q= 10,300 cfs -
T. W. El. 1651. 0 (Curve A)
Valves 50 percent open Q= 7,100 cfs
T. W; El. 1648. 2 (Curve A)
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
PRELlMINARY DESIGN--RESERVOIR ELEVATION 2125 1:i4 SCALE MODEL
30
693
2.7
2.5
2.3
2.1
1.9
1.7
• 0 ........ 1.5
Cl 0
1.3
I.I
0.9
0.7
0.5
0.3 0
~
' ~ ~ -0.5
I•
' \ ---~
• ~
I ~'"--~
' ~
r-....
" ......
~
"'
"""
FIGURE 12 REPORT HYD-562
EXPLANATION
e - 25% VALVE OPENING
/::;, - 50 % VALVE OPENING
0 - 75 % VALVE OPENING
o - 100 % VALVE OPENING
-::- WITH CURTAIN AT END OF TUNNEL
I I I I ,'--Qw= 4,200 CFS
~~ r-....
r--.... •
,-Qw=7,100 CFS sf
. ~
JJ -. Qw = 9,300 CFS
Qw= 10,300 CFS ~ '
_-r-Fj::: t-- ,-. -~ 1\, ..... .._ {!-Qw=I0,300 CFS ~~ -;, -;,
-1.0 -1.5 -2.0 -2.5
HEAD IN FEET OF WATER IN VALVE CHAMBER
QA = QUANTITY OF AIR IN CFS
Qw = QUANTITY OF WATER IN CFS
ZERO HEAD IS ATMOSPHERIC PRESSURE
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
AIR DEMAND - PRELIMINARY DESIGN
I : 14 SCALE MODEL
FIGURE 13 .R.E F'ORT HYO - 562
.693
,..8411 Fixed cone valves I
-c!, ·o v
I I
I I I I I I I 11 ~14.0~ ~12.o,,.,+<- -30,0'--.;>-l I I 1 , , • I I I 1 ->-' 9.0 --
1 I I l I I r<----51,01
- - --~ ~-3,0' I I I r<--------82.0 1---------1 : I I .~--- -------- 141.0'-------------~
PLAN
I ' i .. . 207.0 .
->, ,--12.0' DIA. Air tunnel I 1 ______ _
I I I
S=0.0095--
--Ring deflector
.... -Half liner ,,. ----------
Baff le-' I
SECTION ON ~
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS BAFFLE PIER ARRANGEMENT
SECOND DESIGN
I : 14 SCALE MODEL
r-U)
+ "' z 0
I-<( I-Cl)
I-<(
z 0
I-<( > w .J w
0:: w I-<(
~ _J -<( I-
693
1677
1675
1673
1671
1669
1667
1665
1663
1661
1659
1657
1655
1653 2
FIGURE 14 REPORT HYO -562
X - 100 % I
e - 75 % Toe of jump at downstream >--- end of half-liner, a - 50%
' V A - 35%
~ @"
CIRCLED POINTS INDICATE I~
"' OBSERVATIONS MADE AT X RESERVOIR ELEVATION 2225 / K! X
i,. ......
. v .... ....... I/ ~ V .... w ~ _i..,.- /
V i.,., .... L,
~ X . - • X V ~ ....
, V i I/
/" / ""t,
~Weir crest at ...., -:,,, _...., -~ elevation 1654
-t--
I i/i ~ ..... JI: •' V (Computed) - t--
V / • • I I I I I ,~ / I ( ~ I V "--- -Toe of jump on upstream side
/ / of downstream row of baffles I I/ (Minimum requirement)
~1 ,
~ { jv I/
~v ..... / ., v
I..,,' V
__... _.;,.- ~, -Toe of jump at downstream -- side of downsteam
baffles
I I I ,.
4 6 8 10
DISCHARGE IN 1000 CFS
NOTE: Model arrangement as shown in Figure 13
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
TAILWATER REQUIREMENTS SECOND DESIGN
I : 14 SCALE MODEL
row of
12
FIGURE 15 REPORT HYD-562
693
,,8411 Fixed cone valves I
I I I
·o c-J _r:-_y_ ____ _. --1- ~
.I I -+------.1~_1 ______ _
'N _7
..._ _ _,_'{__ ·o ai a=:3--r-
I -r- - I ~
~\ g ,_..,......,.,, I q I I .J
I I CD I I
IO .,. I I I :-L,---'--------......,..___....L..-1_ - _t \1?
: I : 1->i f<- 5.83 1
~12.o't-33.01--->i : -~ ~9.62'
i<----51.0'- - --->-j I I I r:--- ---- a2.o'--------:>1
I I :,<14.0~
I I I
I I r:--- - ------ 147.0 1 ---- - -------->-1 PLAN
I I
I-<- - - - - - - - - - - - - - - - 2 0 7. 0 I
.._ 1 /-10.0' Dia. flat bottom horseshoe tunnel
E I J..-----......,&.------------------------,.. ,---~ u Q) --+-+--------.... Q)
0
0
I :1__ -r--
1
---6.5 1 x 14.o' Vertical air duct on <t.
_ -Ring deflector -----
---------
/Baffles
S= 0,0095-, "in :::: L'-El.1643. 45
1--------------------------___,_-~-< .... A----SECTION ON 'l_
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
BAFFLE PIER ARRANGEMENT FOURTH DES I GN
I : 14 SCALE MODEL
693
r--ID
+ rt)
z 0
I-<( I-fl)
I-<(
z 0
I-<(
> LL.I ...J LL.I
a: LL.I I-<(
31:: ...J
<( I-
1675
74
73
Toe of jump near the I ,. ~ - 43 foot diameter barrel~ --~ ' 72
71
1670
fl ~ ~
~ ~ :::---~ ~ v-
69
68
67
66
1665
64
63
62
61
1660
1/,...Design tailwater for
V 15 foot high weir---/ at portal ·~ ~
r V Toe of jump at ~ ~
upstream baffle!ii _ /rfV /;, ,I
~ / v· , •\ -
~ ~~ tr /, V~ / rl
~ V -1 .A.,,, ,., ..... 0 V ~ ."' /
/ - ~~1 .,..ll, _ ... I 0- ,..... ,, --- ~ ...
~
~ i-~;s-
-
-- \\. ~ "" ~ ir
/ i,c:. ~ / ,; ,,,. .,,,, .· ~
L I"' ~
I ,I
FIGURE 16 REPORT HYD-562
-
-----~~ ,)>
_.-4...J /.,,
~ V
V v3 Ii
,,,, .. 1/' .,,,, . ~ /
.. - ,,,· / .• J
,h / V Toe of jump at
downstream baffles I--
with three upstream -baffles removed
I I
,Toe of jump at downstream I--
baffles I I I I 59
58 3 4 5 6 7 8 9 10 II 12 13
TUNNEL DISCHARGE IN 1000 CFS
NOTE: The model arrangement as shown in Figure 15 except as noted
z 2200 1------+---+-----1------+----I EXPLANATION
0
I~ 2 I 00 1----+---ft-''.-'-'---=--t-~~--t-=---t ILi ...J ILi
a: 0 >
20001----+-----i+--J-1-p.-t-9"--+---+----t
a: 19 0 0 t------t---.J--,fr--..N---t---+---t-----t LL.I fl)
ILi a:
1700 ...__......_ __ ...._ __________ _
0 2 3 4 5 6
O - 100 % VALVE OPENING
0 - 75 % VALVE OPENING
b.- 50 % VALVE OPENING
@-100 % VALVE OPENING WITH THE THREE UPSTREAM BAFFLES REMOVED (ONE POINT ONLY)
WATER SURFACE FLUCTU~TION AT STATION 13+67
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
TAILWATER REQUIREMENTS
I : 14 SCALE MODEL
FIGURE ·_17 · REPORT HYO - 562
II
~-2'-~ I ' I~ "'~.84~ ,,,~~
-L-- - I,_, \ __ I s 4 ~_, ~--r-,
I
-'
20 I
-~ I
2
TOP OF BAFFLE Piezometer locations../
PLAN VIEW
.12'
PIEZOMETER CORNER
DETAIL EXPLANATION
le ,,i I
SYMBOL DISCHARGE 10,300 CFS
T.W. ELEVATION
1657 AND 1669
I I
-t-_7 1J-~g-i -----------2,20
I . NOTES
Valves 100% open I
- I IO ..... Numbers designate piezometers 'II"
I I I I _t_~ '4J~c::!bLgt ___________ - -- _:_ _____ , ,21
---4--k -- · _______ --- 14' ----------------·>!
I I
a:: ..- IU
40
a:: I- 30 IU C( I- 3i= IU IL.
~ 0 20 z· C( t :E1 a:: IU 10 l&I a:: I- ::::, C( (/)
3i= i3 0 -- a::
a..
-JO
,, r'-. v2
.SI DE OF BAFFLE
" 13-...
7/ t \
~
\ ._:s __...14
' l/3 '"' I'-.... /S
4/ " ~ 's ,,,,
l/16 I~ i-----.. f=:';;- -- '12
~
,-10
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
693
UPSTREAM BAFFLE PIER PIEZOMETERS AND PRESSURES
I : 14 SCALE MODEL
21-
V V
20~
11--
FIGURE 18 REPORT HYD-562
19
2
TOP OF BAFFLE Piezometer locations.,'
PLAN VIEW
1<--2·-~ I 1 1-\,
-!, ~,841-<,- I ,.,.~ _J. __ I ,,. ~
I 5 4 ·°>~, -;J:-- 6----3,19 Pl EZOMETER CORNER
I DETAIL I
-' IO l'-
'3' I I I -l-l 19 :f_g_i-----------2,lO I I I I -~
.;
SYMBOL
EXPLANATION
RESERVOIR EL. 2150
2150
DISCHARGE 10,300 CFS
10, 300 CFS
NOTES
Valves 100% open I I I I
Numbers designote piezometers
t_1:s 141!11~-lf-----------------------1,21
--7- . I 't k ------------ 14 '-----------------:1>-l
I I
SIDE OF BAFFLE
40
13'-~
7'-~) _, ~ " ,-14
'-2 /2 ~6
\~ ;:::,.... ,.11 ~ -• r\. )!I )6 ~
' £3 L,45'. v,, 14.l \.a ' 9 -10 .,11
' -12
I ', I ' ~I- "2 -:-3- ~ .. -'!I '', .,., i-11 .,,, ', ... - "" - .,10 17 .,.
-10 15 -- - c'- --~
r... ....... '12 -- '11
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
693
DOWNSTREAM BAFFLE PIER PIEZOMETERS AND PRESSURES
I ; 14 SCALE MODEL
/ V ~20
It, /
. 'i, - ~;
T. W. EL. 1669
16 57
v- 21
-- ... 21
,-.. - . ··~--
Discharge T.W. in el
cfs in ft ..
10,300 1557:.59 10,300 . 1657-69 10,300 1657..-69 10,300 1657'-69 11,500 I 1658-70 11,500 . 1658.,-70 11,500 . · · 1658-70 11,500 1658-70 10,300 1669. 10,300 1669 10,300. 1669 10,300 . 1669 10,300. 1669 10,300. 1657 10,300 1657 10,300 1657 10,300 1.657 10,300 1657 11,500 1670. 11,500 1670 11,500 1670 11,500_ 1670 11,500 1670 11,500 1658 11,500 1658 11,500 1658 11,500 1658 11,500 ·1658
*Upstream baffle. **Downstream baffle.
Piezometer No.
'5* : 6*
7* 10*
5* 6*. 7*
10* 5** 6**
13** 14** 16**
5** 6**
13** 14** 16**
5** 6**
13** 14** 16**
5** 6**
13** 14** 16**
***Extreme maximum· or minimum. Zero pressure is atmospheric. VP = vapor pressure.
Pressures in feet of water
Ex min*** Min Avg Max Ex max***
-25 -10 -3 3 19 -4 14 35 67 91 11 25 36 52 77
VP -17 -6 5 30 ·-29 -11 ' -3 1. 24 ·-10 14. 37 56 98
12 28 39: !56 85 VP -21 -7 7 38
0 4 ' 7 .. 11 15 3 8 13. 20 34
17 21 27 35, 45 -14 3 ' 14 25 31 . -6 3 11 20 28
-1 0 1 3 4 -1 4 13 25 35
· 18 22 29 41 60 VP -11 8 25 42 -28 -15 -7 3 14 -7 0 4 8 14 0 4 13 27 41
21 25 32 41 57 -17 -3 14 21 39 -15 -7 4 14 21 -4 -1 1 3 4 -4 4 17 31 46 21 25 34 43 63
-28 -8 8 28 42 -29 -18 -7 3 13
PORTAGE MOUNTAIN DEVELOPMENT Low-level Outlet Works
Dynamic Pressures on Baffle Piers 1:14 Scale Model
No. of pressure. fluctuations/second'
A.vg. No. ·_Avg. No. Average reaching. reaching
No . Max Press Min press
12 . 2. 9 2.2 5 1. 6 2.0 9 0, 8 I 1. 3 8 1. 2 1.2
12 2.9 2.51 6 ·_· 2.2. 0.7
10 0.4 0.8 9 0.9 0.8 9 0.3 2.2 2 0.3 0.5 7 0.3 0.1 7 0. 8 . 1.1 9 0.3 0.5
11 2.2 5.3 2 0.3 0.3 6 0.3 0.'5 7 0.3 0.3
10 o. 7 0.3 10 1. 3 2.9
2 0.3 0.3 7 1.1 0.1 6 0.5 0.5
10 0.5 0.7 13 2.4 3.2 3 1. 9 1. 3 6 1. 2 0.5 7 0.5 0.1
10 0.7 0.5
80
70
0:: 60
I.LI I-<X ~ 50
IL. 0
I- 40 I.LI I.LI IL.
I 30
Cl Cl I.LI
20 :l::
I.LI 0:: :::::,
10 Cl) Cl) I.LI 0:: 0..
0
-10
-20
693
919
: .
T
i I
I
I I
! I T
I
I I
I
·t I ~ :
T
± . ! . . .
-25;,
4
:
T I
I I I I I
I l
.
: '
-I I I I I I
I I
i.r' --VAPOR PRESSURE
FIGURE 20 REPORT HYD-562
*
2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21
WATER MANOMETER FLUCTUATION
PIEZOMETER NUMBER
EXPLANATION
f EXTREME MAXI MUM . r--,
,--1· ! I I DYNAMIC PRESSURE FLUCTUATION _j \.._ WHOSE LIMITS ARE EXCEEDED
'1 ( ONLY ABOUT 5 PERCENT ,.__ I OF THE TIME.
I I
I l t--" . o EXTREME MINIMUM
NOTES: PRESSURES NOT AFFECTED BY TAILWATER. VALVES FULLY OPEN.
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
UPSTREAM BAFFLE PIER PRESSURE FLUCTUATIONS 10,300 CFS -- VALVES FULLY OPEN
I : 14 SCALE MODEL
FIGURE 21 REPORT HY0-562
2.8
2.6
2.4
2.2
2.0
!II 1.8 a
' 1
I
\ \ " ' C
a 1.6 '~ ~ "\
' r--.... 1.4
1.2 CJ.... ......
1.0 e.. ....
I\ ~ ~
-f""'-,,.
r-- .....
EXPLANATION
e - 25% VALVE OPENING
t::.- 50% VALVE OPENING
CJ - 75 % VALVE OPENING
O -100% VALVE OPENING
--Q = 4,200
~ r-,,.. r-,,.. ,_Q = 7, I 00 r---. r-,,.. .,,.-..... i,
-.... r-,,.. K: T0-30.8@ r-,,.. ~ _,..Q = 9,300 11"1. QA= ZERO , v
/ ,
J I -
I I I
~ -0,= 10,300 I ru -- ;
693
0.8
0.6 -0.5
-~ - I
I
Q = 11,500-
I I I -1.0 -1.5 -2.0 -2.5 -3.0
HEAD IN VALVE CHAMBER IN FEET OF WATER
NOTE: THE MODEL ARRANGEMENT INCLUDED A 6.5 X 14.0 FOOT AIR TUNNEL OUTLET AT CROWN OF 43 FOOT DIAMETER BARREL.
QA = QUANTITY OF AIR IN CFS
Ow = QUAN Tl TY OF WATER IN CFS
ZERO HEAD IS ATMOSPHERIC PRESSURE
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
AIR DEMAND - FOURTH AND FINAL DESIGNS
I : 14 SCALE MODEL
I
>-,_-'1T'
-3.5
693
2-84" Fixed cone valves-,
',
,,--Deflector ring I
I
~::;:==z:'.'.:::~~:::::~::~:z===z:=:=2:==::::::::;=::::::::==:2:::2::=:z:
Flow
Al
=II)
' -,.,
- ' "' ~ '
, Conical surfaces--' -<_J
B
PLAN
,,Air tunnel
,-<t, Diversion tunnel
SECTION A-A ON VALVE i
__ ft. Diversion tunnel
,,_-<t_ 84 "' Dio. vol ve
94" Dio.
Flow
~ valve-, •
'I
~ I I
I I
I I I I I I I I I ,.
er -,<)
-II)
I I
I I I I I I I I
: ,,Jet spring I/ point
' j==~~HE~~~~----:,--1 96"0
Ful I open sleeve--~---
DETAIL X
'··--cone
__ ct_ Diversion tunnel /
tunnel
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
PROPOSED DOKAN FILLET ~
"' .., ..., o-
"'"' -1 C :0
~"' o,.., IN
"' m N
Figure 23 Report No. Hyd-562
A. Dokan fill.et installed
B. Reservoir El. 2125, 10, 000 cfs T. W. El. 1669.2
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
OPERATION WITH DOKAN FILLET 1:14 SCALE MODEL
42
Figure 24 Report No. Hyd-562
Mean C onjuc!Jate Depths for
Hy, raulic Ju.mo Total energy Number and Tunnel velocity dl at
arrangement discharJe* at (measured at d2 Sta 13+67 of baffles (cfs Sta 13+67 Sta 13+6'7) Computed (hv + d1)
(ft/sec) (ft) (ft) (ft)
Fourth Design, 11,300 38.6 8.6 23.5 31. 7 2 rows of baffles 8 total 10,300 36.5 8.4 21. 2 29.1
Upstream row removed 11,300 40.0 8.4 24.2 33.3
Five baffles in down-stream row 10,300 37.7 8.2 21.7 30.3
All baffles 11,300 45.2 7.6 26.0 39.3 removed
10,300 42.9 7.4 23.5 36. 0
Ring deflec- 31. 0 tor and (jump baffles About swept out removed 10,300 71. 5 5.0 of tunnel) 84.5
*Valves fully open
PORTAGE MOUNTAIN DEVELOPMENT Low-level Outlet Works
Flow Energy at Sta 13+67 1:14 Scale Model
43
Figure 25 Report No. Hyd-562
A. Jet trajectory from barrel liner extends beyond entrance to overhead air twmel.
B. Flow sweeps out of tunnel.
RESERVOIR ELEVATION 2125, Q = 10, 000 cfs NO PORTAL WEIR
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
OPERATION WITH RING DEFLECTOR AND BAFFLES REMOVED 1:14 SCALE MODEL
44 .
693
,.._ U)
+ IC')
<i. I-(/)
z 0
I-<(
> uJ ...J uJ
0:: uJ I-<(
31: ...J
<(
I-
1676
1674
1672
1670
1668
1666
1664
1662
1660
1658 4
V I
I
/ /
/ ~ /
/ /> Curve ·A" ---~v" /
/'f" / /'P /'f:J
..ill' i' ~v ~ ~- --- Curve 11811
V ,. ~
I/ .v V
V I/
5 6 7 8 9 10
DISCHARGE IN 1000 cfs
EXPLANATION
Curve 11A11 is the tailwater required to maintain the toe of jump at Sta. 16 + 78
Curve 11B11 is the tailwater required to maintain the toe of jump at Sta. 16,. 36
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
Fl GUR E 26 REPORT HYD-562.
/~
/
11
TAILWATER REQUIREMENTS FOR A HYDRAULIC JUMP FINAL DESIGN
I : 14 SCALE MODEL
------------------------------------------------------------:0 $ ~ ~ ~~
I-L&J +20 L&J
,._ I\ V
~
z +10
L&J ...J <( 0 -(.) (/)
...J <( -10 (.)
I-a:
-20 L&J I~
->
17+20
VALVES FULLY OPEN DISCHARGING 11,100 CFS
FLOW --;--MAX. --- -----....... S = 0.0095--~ JI---
-
1/ I ---~- ~ k ---Final design Ii
......... I ~
~ ~ l I ,,,- I ::'T - p I I' .
I MIN:-/ - , re 1m1 L _____ I ' ------- ------ ---.....,µ Des1g
ner
nary n
I Liner
17+00 16+80 16+60
STATIONS
EXPLANATION
16+40 16+20
Ave. - Average impingement profile of the main flow. Mox. - Average maximum profile of waves and spray. Min. - Average minimum profile of the main flow.
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
WATER SURFACE PROFILE THROUGH THE . LINED SECTION
I : 14 SCALE MODEL
I I
16+00
o:0 G) -IC
::0 ~m 0 I I\)
UI --.,
en N
693
... 0 +-0 Q) .... Q)
0
0
j 1
=~ ..;,,
---
FIGURE 28 REPORT HYD-562
48 1 Dia. horseshoe tunnel-.."' ,..8411 Fixed cone valves
/
.... ---Ring Deflector
I I I I I I
~2.0~-32.921- -~ I
I
I I
~ ---51.081- - --->1
I I I I I k--- ---- -----13401-- -- --- -----::,..I I . I
PLAN
' ' \ ~
I-<---- -- ---------- 207.0 1 ---- - - - ------~
I I I I/
I LA---6.51 X
== ,.-..6.5' ~ ..., rlim t
- 1111 Ill -~
p---10.01 Dia. flat bottom horseshoe tunnel
14.01
Air tunnel - -
Vertical air duct on l
I\/
,/' S = 0.0095--~
SECTION ON <i.
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
FINAL DESIGN
I : 14 SCALE MODEL
0( -....., -
)
s
---
~_;,-
~
'--
Figure 29 Report No. Hyd-562
Side view of lined section
Angle view of lined section
Looking upstream
PORT AGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
FINAL DESIGN (MODEL) 1:14 SCALE MODEL
48
RESERVOIR ELEVATION 1700, Discharge 2, 500 cfs RESERVOIR ELEVATION 2000, Discharge 8,500 cfs
RESERVOIR ELEVATION 1780, Discharge 4,900 cfs RESERVOIR ELEVATION 2125, Discharge 10, 000 cfs
RESERVOIR ELEVATION 1900, Discharge 7,100 cfs RESERVOIR ELEVATION 2225; Discharge 11, 100 cfs
Note: Valves fully open
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
FINAL DESIGN
Figure 31 Report No. Hyd-562
RESERVOIR ELEVATION 1700, Discharge 2, 500 cfs
RESERVOIR ELEVATION 1780, Discharge 4,900 cfs
RESERVOIR ELEVATION 1900, Discharge 7,100 cfs
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
FINAL DESIGN DISCHARGE THROUGH THE BARREL LINER
1:14 SCALE MODEL
50
RESERVOIR ELEVATION 2000, Discharge 8, 500 cfs
RESERVOIR ELEVATION 2125, Discharge 10,000 cfs
rnSERVOIR ELEVATION 2225, Discharge 11, 100 cfs
PORTAGE MOUNTAlli DEVELOPMENT LOW LEVEL OUTLET WORKS
FlliAL DESIGN DISCHARGE THROUGH THE BARREL LrnER
1:14 SCALE MODEL
51
Figure 32 · Report No. Hyd-562
Note: Valvesnilly open
Figure 33 Report No. Hyd-562
Note: Valvesabout 30 percent open.
Flow through lined section
Looking upstream
Flow through barrel liner
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
FINAL DESIGN RESERVOIR ELEVATION 2125, DISCHARGE 5, 000 CFS
1:14 SCALE MODEL
52
693
FIGURE:-'34'~ REPO'R-T HYD-562
170
2 16 0
15 0
a:: 14 0 ILi I-
r2 ILi ::E 13 0 0 1\ z c( I ::E 12 0 II
a:: I 3 I
ILi I \ I-
c( II 0 3: i \ >-
I \ IXI 100
C 3 \ ILi a::
\ \ ::::> (/) 9 0 I c(
\ ILi ::E I
(/) 8 0 \ \ c( \ \ a:: , \ ILi 7 0 I-
\ \ c(
3: \\ LL
y· I
t-<i5.5'i7-I I
-LI)
SI DE ELEVATION
EXPLANATION
SYMBOL DISCHARGE: i II ,500 CFS 10, 300 c:Fs ;-
NOTES
Valves 100% open J;
. :~ ..... ·. .. .
0 6 0
\ ' These pressures were not affected·· I- \ ILi \ ILi 50 LL
I \ I
by a change in toilwater el~dtio~.
ILi ;\ ~ 4 0
1.........__1(lN5) \\ (/) (/)
\' ILi a:: 3 0 a.. .
\
20H--+-+----+-+----!--+--t--+-+--+--,--+----fH
- 7{:i~~) ' 0 l---l-------,.-------1---+-l-\-+---+---+--____ +-I
/I I§
-5.o'-~1: ... -:::::1L_J _ _L_J~4~l4::~=:t:5~-....~5~-:r:;-;-::b-.-.L._Jl§J6 2 4 6 8 10 12 14 16 18 20 22 24
DISTANCE BETWEEN PIEZOMETERS - FEET
------DOWNSTREAM FACE OF VALVES
PORTAGE MOUNTAIN DEVELOPMENT. LOW LEVEL OUTLET WORKS
LINER WALL PIEZOMETERS AND PRESSURES
I : 14 SCALE MODEL
., . (· ~ : ·-~
, <.:
FIGURE ~5. RE PORT· HYO .,..,562·,
120
110
100
90
0: ILi 80 ... ILi a:: ::tw
~ ~ 70 ; 3: 0: LL ILi O 60 ... C ~ 3 LL
> I 50 mW ca:: ILi::::, 0: (/) :::, (I) 40 (/) w C a:: ILlf:L :IE (/)
C
693
30
20
10
0
-10
I
I
9
9
·;r. o..-;
...
\ \ 2
\ \
\ \. 2 \·
\ \ \ , I 3
\ I \
i 3 \
\ \ I \ \ \ I 10 I
101~
'II
I 2 3 9 10 II
., .. ".
... 121\
' 13
.. \ 12f1- \ . ' ... . \.-
. : .· .,. 1-~" \ - : ,· ,, 14
14
... -20
...
20
\ .
I
.. · \ I .. ..
~22 21 22
4 5 6 7 8 I I I I
I
' ' '
\ \
\
~ -~-\
I \.
'y> \ \
\ ·o, .,
', \ ' \ ', \ ,,,
I
@) I
PIEZOME TER NUMBERS LOCATIONS
"DOWNSTREAM AND
LOOKING
s
EXPLANATION.
YMBOL. DISCHARGE
11-,.500 CFS
10,300 CFS
:r.w. ,. :r.w. ,166~ ~ ~----~~ ,T.W. 1670
~ T.W. 1658
4 5 · 6 ·7 ·8 12 ·13 14' 15 16 17 18 19 PORTAGE
MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
· 20 21 22 .. PIEZOMETERS
RING DEFLECTOR PIEZOMETERS AND PRESSURES
I : 14 SCALE MODEL
No. of pressure Pressures in feet of water fluctuations/second
Discharge T. W. Piezometers Avg No. Avg No. in el in Ex Ex Average reaching reaching
No. cfs ft
10,300 1657 & 1669 1* 10,300 1657 & 1669 2* 10,300 1657 & 1669 3* 10,300 1657 & 1669 4* 10,300 1657 & 1669 5* 10,300 1657 & 1669 6* 11,500 1658 & 1670 1* 11,500 1658 & 1670 2* 11,500 1658 & 1670 3* 11,500 1658 & 1670 4* 11,500 1658 & 1670 5* 11,500 1658 & 1670 6* 10,300 1669 & 1657 12** 10,300 1669 & 1657 13** 10,300 1669 & 1657 14** 10,300 1669 & 1657 15** 11,500 1670 & 1658 12** 11,500 1670 & 1658 13** 11, 500 1670 & 1658 14** 11, 500 1670 & 1658 15**
*Piezometers in wall of liner. **Piezometers in ring deflector. ***Extreme maximum or minimum. Zero pressure is atmospheric. VP= vapor pressure.
min***
-12 VP
7 -5
-10 -6
-17 -30 -7
-10 -11 -6
0 0
-28 VP
-7 -7
VP VP
Min Avq Max max***
-4 3 11 49 -10 130 310 430
58 112 210 322 -3 2 7 10 -3 1 6 24 0 4 12 39
-6 2 14 49 28 196 378 476 56 126 224 350 -1 3 7 15 -3 1 6 24
0 6 14 42 28 77 140 220 24 70 133 160
7 47 94 160 -22 2 14 44
35 91 175 250 35 84 160 225
0 66 150 230 -30 -7 17 39
PORTAGE MOUNTAIN DEVELOPMENT Low-level Outlet Works
19 15 19 25 19 16 17 14 18 25 19 15 13
7 12
5 12
7 12
6
Dynamic Pressures in Barrel Liner and Deflector Ring 1:14 Scale Model
max oress min press
3.9 3.9 2.7 0.9 5.8 4.0 -.- --1. 6 2.2 2.4 2.0 4.8 3.5 3.2 2.3 3.7 Z:4 2.5 2.9 3.3 2.5 3.7 2.3 1. 7 1.0 0.6 0.5 2.9 2.9 1.1 0.7 2.0 1. 7 0.8 1.0 2.3 1. 6 1.1 0.8
FIGURE 37 EPORT HYO - 562
--AIR DUCT
I
--10.9'- -, ./· WALL PIEZOMETER _ I ,VALVE CHAMBER r-5~5~
• ~- PROBE ;f I i PIEZOMETER-.... : I _ I
_I o .. .. T
I I I I
'-TWO 84-INCH FIXED CONE VALVES
----- ----- -- -- - -441-11 11-- - - --- - - - ---
WALL /' PIEZOMETER, 1
I/
693
,/I / I I
I
RING DEFLECTOR-----
.... .... -DETAIL A
SECTION ON i OF BARREL LINER
..-PROBE PIEZOMETER
,I ·~ ,.,.
i ',~--------~ I I
~--- - - -7. 75 '-- - - ---~
DETAIL A
NOTE: CIRCLED NUMBERS DESIGNATE PIEZOMETER LOCATION
SECTION LOOKING DOWNSTREAM
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
BARREL LINER PIEZOMETER LOCATIONS
I : 14 SCALE MODEL
GI <O
"'
(/)
Cl z 0 0 i.i (/)
z
0
Aiii~:~if5'Pi~z. # 13 Piez.#21 2 divisions = 14.0'
Ave. Press. = +65' 10 divisions = 14.0' Ave. Press. = +l.O'
For explanation, see Figure 37
Piez. # 15 5 divisions = 14.0'
Ave. Press. = - 5.0'
Piez. # 2C1 4 divisions = 14.0' Ave. Press. = + 36'
Piez.# 22 20 divisions = 14.0' Ave. Press.·= +3.0'
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
Piez.# 14 2 divisions = 14.0' Ave. Press.=+40'
Probe in jet. 200 divisions = 14.0' Ave. Press. = -o.s'
SIMULTANEOUS DYNAMIC PRESSURES - VALVES FULLY OPEN - RESERVOIR ELEVATION 2125 I : 14 SCALE MODEL
Valve chamber wall 250 divisions= 14.0' Ave. Press. = - 0.6'
::0
"' -0 "Tl o_ ::0 G)
-le :c ::0 -< ITI e,
(>I
u, CD
"' "'
r-------------------------------------------------------------------------=-Ill
'° "'
"' 0 z 8 l&I 1/1
!: l&I :I! ...
0 ATMOSPHERIC ,---
PRESSURE--- Piez. # 13 2 divisions = 14.0'
Ave. Press.= +84.'
Piez.#21 10 divisions = 14.0' Ave. Press.= +1.0'
Piez.#15 10 divisions = 14.0'
·Ave. Press. = - 1.0'
Piez.#20 2 divisions = 14.o·
Ave. Press. • +42.'
Piez. #22 20 divisions = 14.0' Ave. Press. = + 3'
Piez. # 14 Probe in jet. 1 division = 14.0' 100 divisions = 14.0'
Ave. Press.= +55' Ave. Press.= -0.3'
For explanation, see Figure 37
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
SIMULTANEOUS DYNAMIC PRESSURES - VALVES FULLY OPEN - RESERVOIR ELEVATION 2225
I : 14 SCALE MODEL
Valve chamber wall 100 divisions = 14.0' Ave. Press.= -o.7'
... ,, .... o-:a G) -iC
:0
!"' 0 I"' (JI co GI ro
FLOW~
693
..,,,..------~ --- 15°
\#,,<-s\i-- ,!, ------------L
FIGURE 40 REPORT HYD-562
SQUARE CORNER-.., ------OFFSET SUFFICIENTLY TO ACCOMMODATE ' .... , WELD WITHOUT GRINDING.
SCHEME NO. I
/ /
/
/
/ ,, ,,
SCHEME NO. 2
,.,.. ., _. -THIS DESIGN WILL PERMIT THE
USE OF A RECTANGULAR PLATE AND SIMPLIFY FABRICATION.
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL OUTLET WORKS
PROPOSED MODIFICATIONS TO RING DEFLECTOR
Figure 41 Report No. Hyd-562
Note: Right valve fully open. Left valve closed. Discharge 5, 000 cfs.
Flow through lined section
Looking upstream
17+23.6::i _ ·...,.: t - - ··~:~:J,
Flow through barrel liner
PORTAGE MOUNTAlli DEVELOPMENT LOW LEVEL OUTLET WORKS
FINAL DESIGN RESERVOIR ELEVATION 2125--0NE-VALVE OPERATION
1:14 SCALE MODEL . . .. .
60
· 600
I-LaJ LaJ IL
500 (/)
LaJ > ..J <(
> LaJ :::c 400 ...... :IE 0 a:: IL
:E <(.
300 ILi a:: I-(/)
a.. ::::>
I-ILi
200 ILi IL
,.._
0 <(
LaJ :::c
100 ..J <( I-0 I-
0
§.93
FI GAHi E~ i4.2; • . RE PQR_T q-1yp J. 5~J.
,--....,..........,,---r---,-..,.... ...... - ............. -...-....,...-,--....,... ....... - .............. - ....... --...--,---...--....---,,-, ...... , ......... - 120 I
t--+--t---+----t,---+---+--+--+"--+--+--+--+---+---+----+--+----+--+-....... -t-,"'J,I _i ... _ -~-·---1,---t II 0 I.
I ---------------~-------------1-:..,i_,-,-+,· ~""'"""'-t 100 . .II -
t---+---11--+---+-+--+-+---+-+--+-t---+----l-+---+-+---+-+--+~~I .l-~;..-.,1----1 J
t--+--t---+---+-+---+--+--+-.-+--+----+--t---+---+-+---+-----+--+--+-J , 1'"+~--1""-~-,....,_/: = 90 I I :~
I • I I
-+-~-t----+--+---+-l<---11,i,-+-l--+-~/1~ : t----+--t---+---t--+---+-+-_, ' o"', , , t---+--l---+-----1--+---+--1-_..,., '-1--+-+---+--1---+-,-#-'-+---+--1--~-.J II I o\0,1.,_.1-+-+----+---I
----------~-'------+-·~~- ~ ~~6~--------1----+-----.l---+-----I--+---+- ~! ~I+--+-+-- ~ I\., - ,,'>-11---+--+-+----4
l1 I II .I 0 I II .I
__ .......,1---+---t--+----t-t ' / ,I " ,I
l----+--r---+-----1--+-- l,Jl-+1-+--+-t---+-#l-+---+-+--n~I'~ .l_+.,<,1-+~+--+----lf---+i--+--t I---+---+-+--+--,___ g-,_:1-_1----..,1--_--l+_-_--++_-_-.,.+;,..,-l __ -++-_-_-+1-----_11---:-~l~~l:};~t"t-1<----11-----1+_-_--++..;.~_-,.+-... -_-,.+-~'---;-t-----11
l----+---,r---+-----1-~ 1,J1--'+---+-+--+~l---+---+--H....+--hl'':.....+-+--+-t---+----ll-'--+---t 1----+--t---+----+-~l--,--+-+---+-+-~-+--+---,~-+---.l'"--+---+--+--+-,--+--+-:--t---1
II
I II
I I
8Q
70 •.)
60 ~,,
'-'.,
50
l---+---+-+--+-~7:A---+-+---+-~-+-+--+-#-ll----hll~-+---+-+---+.._+--+-.. -,,1-,-.,-t.q I ,, ,,I
,l,I " " ,,I
I ,I ,. ,,I
I ,I I , ,,I
I ,I
' I ., I
f I
I ,I
I ,, I ,,I - ~
I/
" ... ,I ., 1.-~:;~'.::::::t:;~-~~:~::--::i::::i::::i::::i::~~=~~=~==~~=+==+==+==;::::~:::~:;:::::~:~ 10
" .... _._ ..... , .,
2 3 4 5 6 7 8.
DISCHARGE IN 1000 CFS BOTH
NOTATION: HEAD LOSS FROM DIVERSIOl')I.; TUNNEL ONE DIAMETER UPSTREAM OF PLUG TO CONDUIT ONE DIAMETER UPSTREAM OF VALVE = ENTRANCE LOSS + CONDUIT FRICTION LOSS.
FRICTION LOSS = f (L/D) (V2f2ol WHERE
ENTRANCE LOSS = 0.1: (V2/2g)
~ VALVES AT ELEVATION 1669.96
'· ·...;. i.
PORT:AGE .. \MOl,JNTAIN· OE:VEL,O,PMENT LOW LEVEL OUTLET WOR.K.S
,. ,. • . ·. . ' . ' ' . . . . . . . ~. !'~; \' ·.: . :. ;
DI.SOH·ARGE: AND HEAD· :Loss -C:URV~S
I : 14' SCALE MODEL
f = 0.0096 L = 2.00.00 ·o,~'"too V· =•- VELOCITY
IN CONDUIT
I-ILi ILi IL
(/) (/)
0 ..J
0 Cl ILi :c
FIGURE 43 REP.ORT HYD-562
... II.I . II.I I&.
I
z 0 .... ci > II.I .J II.I
a:: 0 > a:: II.I (/)
II.I a::
2300
2200
2100
2000
· 1900
1800
1100
1670
0
i..-
., I
., ., I ...
1..r -..,. ---2 3
I I
- I I
I
I
I I I
I o\O, o'e' 00,
~/ ' I ,, I
(!11 I
~ ~I
I I
~I I O.r
~· I
I
"' ::,."f"I I I ,
I I
I I I II
~
7 I
I II I ~
I .,
I
II ., 17 .,
·~ ~
" ,I
4 5 6 7 8 9 10
DISCHARGE IN 1000 CFS
Reservoir Elevation Is equal to Total Head @ valves plus HL from valves to reservoir
693
PORTAGE MOUNTAIN DEVELOPMENT LOW LEVEL Ol}TLET WORKS DISCHARGE CAPACITY CURVES
TWO 84 - INCH FIXED CONE VALVES
I : 14 SCALE MODEL
. I
I
I I
II 12
APPENDIX
Studies to Develop an Energy Dissipator for Jet-flow Gates
Purpose
The purpose of this phase of the model study was to develop the hydraulic design of Portage Mountain Development low-level outlet works utilizing two 84-inch jet-flow gates in each of two diversion tunnels.
Summary
The above-atmospheric pressures obtained at all operating conditions showed that the shape of the bellmouth entrances was satisfactory. Head losses through the model bellmouth entrances and conduits down to the valves closely represented the computed prototype losses. The discharge coefficient of the jet-flow gates was 0. 83 for 100-percent opening. The size of the air vents to the gate slots and downstream conduit was increased from two 24-inchdiameter conduits to one 42-inch-diameter conduit; the maximum air demand was found to be about 2,000 cfs per gate, resulting in a velocity of about 210 feet per second through the 42-inch conduits. The steel liner downstream from the face of the tunnel plug should be lengthened several hundred feet.
A stilling basin 300 feet long with the floor 26 feet below the tunnel invert was required to adequately still the flow. In addition to the basin, a 9-foot-high weir was needed at the downstream portal to provide sufficient tailwater depth for the hydraulic jump; the weir height cannot exceed 9 feet to avoid surges from the hydraulic jump sealing the tunnel. The tunnel must be free of debris to avoid erosion of the concrete by abrasive action of material. in the hydraulic jump.
INTRODUCTION
The initial investigations were concerned with developing an energy dissipator when the outlet works flow was controlled by jet-flow gates. Flow characteristics in the bellmouth entrances, the jetflow gates, tunnel plugs, and the downstream portal were also studied, Figures 1 and 2.
Tests were made with both jet-flow gates simultaneously discharging the maximum capacity of approximately 10,000 and 11,000 cfs at reservoir elevations 2125 and 2225, respectively. Tests were also
63
performed with the gates partially open for flows as low as 5,000 cfs at reservoir elevation 2125 and with the gates fully open for reservoir elevations ranging from 1, 700 to 2, 200 feet. One valve operation was also studied.
THE MODEL
The model was a 1:24 scale reproduction of Diversion Tunnel 2 extending from 288 feet upstream of the tunnel plug down to and including the outlet portal.
The bellmouth entrances to the two conduits through the tunnel plug were machined out of clear plastic; the conduits between the bellmouths and the jet-flow gates were 3-1/2-inch-diameter sheet metal pipes. The jet-flow gates were constructed of'brass, and the conduits downstream from the gates to the downstream end of the tunnel plug were 4-inch-diameter clear plastic pipes.
The 48-foot-diameter horseshoe tunnel downstream from the plug had a sheet metal invert and a clear plastic semicircular top.
The model diversion tunnel was shorte"Q.ed about 23 percent to provide flow velocity similitude between the model and prototype at the exit portal. This correction was based on estimated Manning's roughness coefficients (n) of 0. 009 for sheet metal and 0. 012 for concrete.
The ope:r:-ating head on the gates was measu;red 1-tunnel diameter upstream· from the plug and flow was regulated by simultaneously adjusting the· opening of the jet-flow gates and the discharge.
Tailwater elevation was controlled by means of an adjustable gate at the end of the tail box and was measured by a staff gage located in the downstream end of the discharge channel.
TEE lliVESTIGATION
The Bellmouth Entrances
Previous studies!/ have shown that the bellmouth entrances to the conduits iri the plug should be located a minimum distance away from the boundaries of the diversion tunnels and properly spaced to prevent subatmospheric pressures from occurring on the bellmouth
1/Bureau o~ Reclamation Hydraulic Laboratory Report Hyd-470, "Aerodynamic Model Studies of the Outlet Works Intake Structure for Twin Buttes Dam, San Angelo Project, Texas, 11 by D. Colgate.
64
surfaces. Twenty piezometers were installed on one of the model bellmouths (five each on the crown, invert, and two sides) to confirm these criteria. These piezometers showed that the bellmouth pressures were above atmospheric and therefore satisfactory during operation with both gates either partially or fully opened (Fig. 3). Similarly, all pressures were satisfactory with one gate fully closed.
The pressure data, expressed as a dimensionless pressure factor, te , are given in Figure 4. ~ h equals the piezometric pressure
referred to the conduit center line minus the conduit center line pressure 53. 82 feet downstream from the bellmouth, and hv equals the
velocity head¥: in the conduit.
In the final design, the bellmouths were placed higher in the plug to provide a rock trap in the diversion tunnel and to steepen the angle of flow trom the conduits into a proposed stilling basin. Since the bellmouths were no closer to the tunnel boundary than in the preliminary design, the pressure measurements were not repeated.
The head loss from the diversion tunnel to a point 1-pipe diameter upstream from the gate valves was measured for 2,500 cfs per valve at reservoir elevations 2100 and 2200 and for 5,000 cfs at reservoir elevation 2100. These measurements indicated that the model loss closely represented the computed prototype losses and
varied from about 0. 12- to 0.18 ¥:-Jet-flow Gates
The Portage Mountain 84-inch jet-flow gates were patterned after the gates used for the Trinity Dam auxiliary outlet works]/, Figure 5. Coefficients of discharge computed from the model discharge capacity calibration data, Figure 6, were almost identical to those determined for the Trinity jet-flow gates.
Pressures in the 8-foot-diameter conduit were slightly subatmospheric immediately downstream from the gate slot for the operating
2/Bureau of Reclamation Hydraulic Laboratory Report Hyd-472, "Hydraulic Model Studies of the Trinity Dam Auxiliary Outlet Works Jet-Flow Gate, Central Valley Project, California, 11 by W. P. Simmons, Jr.
65
condition of 2,500 cfs per gate at reservoir elevation 2100. Pressures 40° from the invert were about 2 feet below atmospheric compared to about 5 feet below atmospheric at the invert piezometers in this region.· However, these low-pressure areas appeared to be in an area where the jet had not yet expanded to fill the conduit and were probably due to lack of sufficient air supply from the vents rather than from the flowing water. For 5, 000 cfs per gate at reservoir elevation 2100, the subatmospheric pressures were approximately 10 feet below atmospheric both at the invert and 40° from the invert, and the subatmospheric pressure region appeared to extend more than 1 diameter downstream from the gates. These pressures also appeared· to be in the vented area rather than in the area where the flow was in contact with the boundaries; therefore, additional piezometers were installed farther downstream to determine the pressure pattern in the region of fl.ow contact with the walls.
The additional piezometers showed that as the gates were opened, the point of impact of the jet moved downstream. Upstre~m of the impact area, pressures were below atmospheric; in the impact area the pressures were well above atmospheric; and downstream from the impact area the pressures were near atmospheric.
The size of the air vent was increased from two 24-inch-diameter conduits to one 42-inch-diameter conduit to alleviate the low pressures in the conduit downstream from the gate slots. The increased air supply reduced the instantaneous minimum subatmospheric pressure from 24 feet of water below atmospheric to only 5 feet below atmospheric.
Air demand measurements showed that the airflow increased with increase in head or with increase in gate opening. In general, the ratio of airflow to waterflow increased as the gate opening decreased or as the head increased. These data agreed with the Trinity Dam jet-flow gate test data.
Maximum air demand was approximately 2,000 cfs per conduit supplied through one 42-inch-diameter air duct into the air chamber. Velocity of the air through the duct would be approximately 210 feet per second which is below the recommended maximum limit of · 300 feet per second.
Flow Downstream from the Tunnel Plug
In the preliminary design, the conduits were to be placed no closer than 12 inches from the walls of the 42-foot-diameter steel liner, Figure 1. The 150-foot-long liner was installed in the model horseshoe tunnel so that it was tangent to a point on the outside wall of
66
the conduit portals, and an offset existed between the conduits and the liner on either side of the point of tangency. Piezometers were installed in this area, and the pressures did not exceed 3 to 4 feet of water below atmospheric. The jets were not submerged for the design flow of 5, 000 cfs or for an emergency flow of 10, 000 cfs, Figure 7.
The steel liner extended 150 feet downstream from the conduit portals and formed a vertical offset between the liner and tunnel wall. Although the liner extended beyond the impingement area of the jets, the velocity of the flow at the end of the liner was almost as high as at the conduit portal. Some of the flow backed up and submerged the undernappe of the jet at the offset which could introduce adverse pressure conditions. Therefore, it was felt that a long transition section should be placed between the liner and the horseshoe tunnel or that the liner should be extended farther downstream.
An alternative to lengthening the steel liner was to construct a stilling basin immediately downstream from the tunnel plug to dissipate the energy of the flow leaving the conduits. The model was modified to include a stilling basin and all further investigations were directed toward developing a satisfactory basin.
Stilling Basin in Tunnel
The initial stilling basin development tests were with the tunnel plug conduits placed on an 8° 30' slope discharging into a basin 40 feet wide by 343 feet long with its floor 21. 5 feet below the center line of the conduits, Figure 8. Since the computed tail water depth at Station 11+20 (assuming critical depth at the portal Station 1+87) indicated insufficient depth to maintain the hydraulic jump within the basin at any discharge, a weir was required at or near the tunnel portal to provide sufficient d2 or tailwater depth. 1
The weir height was adjusted so that the basin performed well for flows up to and including the design flow of 5, 000 cfs at reservoir elevation 2100; the surging and waves that developed in the hydrauli~ jump for 5, 000 cfs were not excessive and did not reach tunnel crown. However, the basin appeared to be longer and wider than necessary. With the same weir settings and operating at low reservoir elevations with the gates 100 percent open, the flow submerged the conduit portals at the downstream face of the tunnel plug. Although submerged operation appeared satisfactory, poor flow conditions existed during the transition zone from unsubmerged flow to submerged flow.
The inverts of the conduit portals were raised 9 feet to prevent the submergence during operation at low reservoir levels. In addition to elevating the portals, the conduits were placed 1 foot closer together
67
and the basin was narrowed from 40 to 38 feet. The narrower basin performed well for flows up to and including the design flow of 5, 000 cfs at reservoir elevation 2100. Although the conduit portals were not submerged at lower reservoir elevations, occasionally the flow from both conduits veered to one side or the other and flowed downstream along one of the side walls. Flow returning upstream along the opposite side wall nearly submerged the portal near that wall. However, the flow was sufficiently stable-to be considered a satisfactory operating condition for the short time that --the reservoir would be discharging-at reservoir elevations below 2100. .
For emergency operating conditions with either one gate operation ·· or both gates fully- open qperating at maximum reservoir. elevation, the performance was acceptable. However, the surging in the flow through the tunnel increased with discharge until, at 10, 000 cfs, the tunnel occasionally filled. The surges did not fill the tunnel for 9, 000 cfs at about reservoir elevation 2000, although waves from one side or the other sometimes reached the crown. . .
Data were obtained for this basin to determine how variation in weir height affected hydraulic characteristics of the tunnel such as the location of the jump, jump sweepout, depth of flow at the face of the tunnel plug, depth of fl.ow in tunnel at the downstream end of basin; surges at the portal and tunnel vibration, and audible choking as caused by the surges. ·
These tests showed that the :surges filled the tunnel near the downstream portal causing an audible belching and tunnel vibration when the weir was sufficiently high to prevent the jump from sweeping .out of the .basin. Based on the_se tests, the basin floor was lowered 11 feet to elevation 1616, the sloping apron lengthened to 190 feet, and the basin length was reduced to 300 feet to maintain the same overall length, Figure 9.
The same data obtained on the revised basin determined that the weir crest-should not be higher than elevation 1649 and;that the basin floor should be placed at elevation 1616.. The hydraulic performance of the revised basin was very satisfactory at 5, 000 cfs and acceptable at a discharge of 10, 000 cfs, Figure 10. The surges at the portal occasionally came close to sealing -the tunnel at flows -of 10,000 and 11,000 cfs, but the audible belching effect did .not oc~ur.
At this stage in the investigation, it was decided to use fixed-cone (Howell-Bunger) valves to control the flow through the low-level outlet works and the studies on the jet-flow-gate-controlled scheme were abandoned. The decision to change the type of control was
68
brought about by several considerations including (1) the extremely high cost and difficulties involved in the excavation and construction of stilling basins in the existing diversion tunnels, and (2) the inherent danger of placing a hydraulic jump stilling basin in the tunnel directly under the dam embankment.
This concluded the testing of the 1:24 scale model of the scheme utilizing the jet-flow gates, and the model was rebuilt for studies of the new design.
69
i / t Tunnel----.---['
Oetoi/ i! _/,
y • .J!-.
Fqvat,on,~~ -+(l-"'45)' =I,, ~~-11 x~.
t""------- -3.850' ------>-i
D£TAIL i!
\ ____ /,- Air \vent piping not shown
r----,
I
f""'/8" ·->-;-+ -I I r-:----
... 4'-6"------,
6;o· - - --- - -- -
DC TAIL Y
y A
tc Gote chomber - - , ,-Provi.s/ons for plt/991ng 11 9t;," steel pipes not \ shown.
\
\
- ---------- -· -· 132~0·---
To tvnnel ,..I -----
To tvnnel 'j---
SECTIONAL PL.AN A-A
SCALC: 1"~20'
_,... 5:10:+
tf. l:-84' R. F. Gates· -- ->-i
J:.:;- Ii Ciote c/ivmt!>er I
-<-'
- - so·
SECTION B-B
-134-' Jet ,C.-/c,w Gates
50'
? i
-------- /50' ---- -- -,-;
D-<j
~_,..,.----Steel liner
.8
fj 4i:,: Air Jt,,_,Pply pipe --, 30 Arr s1,;oply pipe- ..:..· _...,....-
vent ii reqvired
Alr vent~ IZ ~dl<:1.
Steel
SE."CTIDN C·C
;.-.-- E Tunnel
I
.s-t,1;:,ply pipe
-'"---~ .... 6"-dia. a/r vents,, ilre1t.-ired
SECTION O·D
•, __ D. 1642.46 !Tunnel It 2) ~ '
r------7 Tunnel No.2 Tunnel Na 3
k( G_O{e Chamber /9•00.57 19 •76.37 Sta A 19,00-73 /9-,.76.53 ___ __:~-
£/ A /653.58 1655.09
Sto: B 17• 68. 57 18 • 44.37
£1, 8 1652.06 1651.57
NOTES
Grout/ng deto/ls not shown.
~----------,----~-------------------4 Re"- 5·31-66 Elev., 1642.46 a( Sta JJ, Tunnel "Z, atft!~d (iL6.
© ALWAYS Tlllnil' SAfETV UNIT£0 STATES
DEPARTMENT 01"' TH£ INTERIOR BUREAU OF RECLAMATION
-r£CHNIC,4t. 4..S.Sl~'TANCE P,!'f()<,~AM
PORTA6E MrN, OEVEl. - PE.ACE RIVER - cA.NAOA
PORTAGE IV/TN. DAM OUTLET WORK5
GATE CHAMBER
T,14GED __
CI-/ECKED_ ~--, ___ APPROVED-i--------·-----------------1 DENVER, co;.a, JAN 23, !9V>§ OA ·- 25 -I
Min. lint! of
Tunnel t,i,inq reinl'o~ I ~~<?1~ft;1nce of' 40'. SttSECTI0NC-C
_TUNNEL __ _
\_
\
N ,-.... -~ \
'°o'-o"
TUNN£L OUTLET iRAN5/TION
.. , ~ "--- Rock Am:hors
-~-10·:o·c'enf~s-eacn way, lyp-
Rock Anchors @10'-d· centru each way, typ.
A-A
!9'-7•
{Tunnel "I EL/637. 66 F: I I Tunnel "2 E/.l6-'700 ~ Tunnel' .3 Et. I 635.tJB
-50'--5•
TUNNcL OUTLET ---~ CHANNEL -
~ SECTION B-B
Tunnel #z I Sfa. l-f-17 ->j
Tunne/#2 · 1 Sfo. 2+47->j
.SECTIONC-C
693
Min Hne of' exca-.ohOn ----•
_ i- -
T'},P/CAL TRANSITION SECTION
DETAIL X
'it Tunnel
SECTION F-F
SECTION E-E
SURFACE DPAIN DETAIL {No Scdfe)
Qt":,fance >( i~ rneasu,--ed up~trearn r,--orn Portal race.
TRAN5IT/ON DATA
-,r
:1
I "
AREA PLAN AT TUNNEL OUTLETS
Exi5fin9 rock /"bet: al £ funnel "I
!
' ' ' '
APPENDIX FIGURE 2. RE.PORT HYO 562
/850
''·y--exisf-in9 roclc ~ al
'-,,, IE f<.mnel "2
1800
/77!5
',,
'\ -. ' ' '
17.SO
17?.J
/700
1(57!5
/650
SECTION G-G SECTIONH-H
1850
1825
1800
177!5
1750
1725
1700
----..... ' ' '
\ ,,.,.--E"isfing rock face al '.J ~ funnel • 3
)
' \ \
\ \
\ \
NOTES I. Alf concrete shown on +f,,s draw1nq shall be
Class A 2, (5000 psi)see Spec1f'icaf/on. c. No groufm9 behind concrele :shat I be carried
oul unl,1 concrefe has cured r'ar o minimum of' 2B days.
3. All rock anchors shown on lhis drawing shall be made rrom /Voll reinf'arcinq bars qroufed 1nio 2·1'nch dia holes drilled to a rn,n:rr,urn deplh of' IO fe,d ti'ifo sound roc:k.
4. All e,rposed coal ond shale seams on fhe oullef channel and powerhouse occess road excavafed fbces to be covered wifh o }a ,'nch layer or pneurnafico/ly opph'ed rnorfor as soon as possible af'ler excavol,"on fo profecf
~:E~:;~~-p;;.:;~~~~""'==--;-D---'-~~== aqainsf loss of' rnoislure. ,,. c " ~ ,., 5 Sides of' ot.Jlief channel and powerhouse 1625 ___ __jgt:i_ I acress rood fo be e,cavoled to .s/op,;,s or'
-----' 4 verl,cal -lo I horizonfal '
SECTIONK-K 6.ror ref"erences see O"""'J U-3005 -/Oc'O 7 Abbrevial1ons :
PF = Fbrlaf 11,ce B For def-a,/5 of rock anchor::, .see Reinforcement
Ow9. U-304-2-4-022
REFERENCE U·300!5-/()20 General Arronqernenf
Sea~ for Area Pion o 50 100 !!Xi av Feet 1aiii:::--=iaai:::===ia---iiia.iiai::::::====i
Scale O 10 20 40 60 80 Feet
Scale Fbr Defail X o._===-5====/0:liiiiiiiiiiiiii/5====:!0j Feel
I i --i
i
' __ (_ i
+-
J'! ! ~ .__B_R_IT_1s_H_c_o_L_u_M_B_1_A_E_L_E_C_T_R_1_c_c_o_M_P_A_N_Y_L_1_M_1_T_E_o _
~ PORTAGE M)UNTAIN DIVERSION TUNNELS
-i!- TUNNEL OUTLET5 i~ PLAN & SECTIONS
-- --r-
U-3005-1023 RI
693
... 20
9 10
::~-· 'j :;i y q
.. ·. 0,-: · ..
---.-1 I I I I I I
Sta . 19 + 68 .57----'
-< X ,---r - - ---3. es'------]
El. 1644 35 ___ -~
.. 0 .
500
'- -- --450
400 0
~ 350
~ lL
300
"' 0..
~ 250 0 I-0 200 v-----0:: 0.. ~
z 150 --,
"' 0:: 100 ::) (/) (/)
50 "' 0:: 0..
0
-50
I.
PIEZOMETER
PIEZOMETERS
5 ANO 10 4 AND 9
3 AND 8 2 AND 7
I AND 6 15 AND 20 14 AND
13 AND 12 AND II AND
_,..l. _:~o~~ c.f.s . , '\.
I 2,500 c.f. s.
•c----~
19
18
17 16
'
LOCATIONS
COORDINATED
X y
1.00 0 .984 2 .DO 0 . 870
3 . 20 0 . 566 3 . 60 0 . 360
3 . 80 0 . 156 1.50 0 .944
2 . 50 0 . 776
3 . 00 0 .638
3 . 50 0.424 3 . 70 0 . 280
'-i;,ooo c.t.s.- 1-- '
.,./ 10,000c.f. s-\
=_,.----f'--,<
-100 "-'---"---'---'----"-''--'---'---L-...UU......L--L-_., __ _.,.,__.__.__., _ _,c,_ _ __, 123 4 5 678 9 10 11121314 15 16171819 20
PIEZOMETER NUMBERS
APPENDIX FIGURE 3 REPORT HY0-562
SECTION A-A
-.., "
LOCATION DIAGRAM (Looking downstream)
LEGEND 5,000 cfs. two vo I ues
Reservoir Elev. 2200 2,500 cfs. one vol ue
Reservoir Elev. 2100 5,ooocfs. two values
Reservoir Elev. 2100 10,000 cfs . t WO VO I ues
Reservoir Elev. 2100
- - ATMOSPHER IC PRESSURE
PORTAGE MOUNTAIN DAM
OUTLET BELL MOUTH
WORKS PRESSURES
I : 24 SCALE MODEL
APPENDIX FIGURE 4 REPORT HYD-562
693
0.4
0 .3
0 .2
.cl> <] .c 0 . 1
l(\Q 'x' X . ~
.., .---~ ---- --...::::: ..... -
0 ~ .............._
-~ ..... "M
~ ·11. -
0
-0. 1 0 0 .05 0 . 10 0 . 15 0 .20 0 .25 0 .30 0 .35 0 .40 0 .45
DISTANCE FROM INLET + CONDUIT DIAMETER
DISCHARGE = 5,000 CFS, RES. EL. 2 I 00 FT., BOTH GATES EQUALLY OPEN
0 .4 .----~----r----r---.....,..-----,,-----,---,------,------,
-0.1 0 0 .05 0 . 10 0 . 15 0 .20 0 .25 0 .30 0 .35 0.40 0.45
DISTANCE FROM INLET CONDUIT DIAMETER
DISCHARGE = 5,000 CFS, RES. EL. 2200 FT., BOTH GATES EQUALLY OPEN
0.4
0 .3
0.2
\ \- _..,
.,..,-.cl> <] .c
0 . 1
0
0--~
:-------~ V' -
~ V
-0. 1 0 0 .05 0 . 10 0 . 15 0.20 0.25 0 . 30 0 .35 0 .40 0 .45
DISTANCE FROM INLET + CONDUIT DIAMETER
DISCHARGE = 10,000 CFS, RES. EL. 2100 FT., BOTH GATES EQUALLY OPEN
NOTES EXPLANATION
t::. h PIEZOM ETER PRESSURE REFERRED TO £. MINUS CONDUIT PRESSURE 53.82 FT . DOWNS TREAM OF BELLMOUTH .
hv VELOCITY HEAD IN CONDUIT .
PORTAGE MOUNTAIN DAM OUTLET WORKS
X = PIEZOMETER 0 = Pl EZOMETE R 0 Pl EZOMETER fj PIEZOMETER
PRESSURE FACTORS FOR BELLMOUTHS
I : 24 SCALE MODEL
NO . I - 5 NO . 7 - 10 NO . II - I 5 NO. 17-20
r £ T,,,., NoiTt-- _ -----
1 :f r -------Li-~ -
•
S•0.00.95_ •
,.A•R F Gates 2-i .,.,. ·
i
.. I>
; .. _·; .· . ' i"
• •. I
p
-· p . ,_. p ..
. ·o ·.
----~t-
--~
----------t---
5£CT!ONAL PUN
2.-'t: J.F. Gates
·p~ ,I
. ()
,6 •
: '.·L> . 6_ . <)
.. ,, . .
. . 5[CT/ON A-A
--- --- 5'-0·
__j A
0 -i:. 0
'10 'a,
t ·!! ,~ i 'I-
<U
! )' it-
t I !
<k
/ /r-7, D M ""1' p,,,. / ~ /
5 desiqnafe Circled r1.1·:m;:.,e;-del pi'eiomder 1,z4 sea e locafians-
/ fhru 7
SECTION /J-.0
--·---- (s i OT SECTION) SEC1/0N B-B ~
or-
.SECTION c-c __
- ;op, Bonnet Cov~r
---.
~NT OF MA TION
Ol!~:~~V OF flf'TE~::CE PROG~~:l<-CANI\DA ASSIS 0.CI! "-
TC.CH~litiroPIJEN.T- P J 11 DAM NTN. MOUNTA "'-PORTAGE ORKS
OUTL£TBi STUDY Gl\T£ CHAM
SVIIMITT~O .••. D-B:_~·-------·-·· ENOEO-. DRAWN..... -----RECOMM
AlfllflROVEO ..••
-t\l I.LI IX :::, (!)
ii:
I- ~ uJ z uJ ~ I.I. 0
:i: en
z 0 en
Cl[
I-~ ct
> LLI I.LI
uJ IL ...J uJ z
...J z ct 0 z ct ~ u Cl[
> I.LI _, I.LI
.. I.LI ~ 0 z -
FIGURE 3 REPORT HYD-564
10----------...... ---------------------------,--------------------------------------
9.0
8.0
Note: Elevation of the south staff gage with respect to the canal elevation is shown on the graph, and was determined by survey levels. Water surface elevations (measured by the water s toge recorder) were referenced· to the south staff gaoe .
2.2
2.1
2.0
1.9
1.8
I. 7
1.6
7.0 "------'------""------.i.-----..... --__ _._ ____ ...._ ____ ..,._ ____ ......_ ____ ....,_ ____ ....... ____ ..... ____ __,, ____ --' ____ __, 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400
SURFACE AREA OF CANAL - SQUARE FEET
VOLUME OF CANAL - CUBIC FEET
ELEVATION - SEEPAGE AREA AND CANAL VOLUME
29
I-uJ uJ I.I.
z 0 I-<( > w ...J uJ
uJ C)
ct C)
I.I. I.I..
~ (/)
.:I: I-=> 0 (/)
Appendix Figure 7 Report No. Hyd-562
A. Both gates discharging 5, 000 cfs Reservoir EL 2100. Looking downstream.
B. Both gates discharging 5, 000 cfs Reservoir El. 2100. Looking downstream.
C. Left gate discharging 2, 500 cfs Reservoir El. 2100.
PORT AGE MOUNTAIN DAM OUTLET WORKS
F LOW IN PRELTh1INARY DESIGN 1:24 SCALE MODEL
693
APPENDIX FIGURE 6 REPORT HYO- 562
0.9---------------------........ ----
0.8
0.7
Heads across gate ranged from 100 to 525 feet.
Q
Aj2g ~H
Q = Discharge in cfs A = Area of orifice in sq. ft.
~H = Total head one diameter upstream of gate minus ambient pressure downstream of gate in feet.
"O (.)
w <.!)
a:: <I :I: (.) (/)
0
u... 0
~ z w -(.)
u... u... w 0 (.)
0.6
0.5
0.4
0.3
0.21------+-----#----4-------l------+----~
0.11------~--------+--------I-------+----~
0-c;.... ___ 1...-___ ___., ____ ......1.. ____ ....1.,.. ___ ___,j
0 20 40 60 80 100
GATE OPENING - % EFFECTIVE TRAVEL
PORTAGE MOUNTAIN DAM OUTLET WORKS
COEFFICIENT OF DISCHARGE - - 84-INCH JET FLOW GATE
I : 24 SCALE MODEL
-- ·symmetrical obovt I!: tvr,,ne/
r Vary ,-,,trances betweea ....-, tnese eleKJt/ons--- t
,,- -~ ----n. /680.53, Max. ·~-'-.J-~'c,,. , :_ ,P ~; f\. - . : •
,~ :_;:._./. _., ---MOl<. rod - 15 ;1 / ,---- \ ,- El. l6M!3G ' u<+ ,
-<--zo:o·... '-B4"I.o. sreel pl,oe
SECTION A-A STA. I~ +6IJ~7
Bl 1 /--Sta. /7r68.!>7 µ--
Sv99e:.ted limits
--<- -I
of transliJor, - ~
-- -11z' to e.oo'
.,,_---SymP1etrical oaout E z'unnt!JI
5£CT!ON B-B
---~ '
- - - i,,.-1 -- ~:,
----Bu/~ci /?Jodel to accc,,nrncdate 'the len9t/1 ,,noss/6/e cl7on9e.~ /i? tronsit1017
PROF/;_£ ON 'l. TUNNEL
I
,-J-<-1 I,
--~
''-:5,,// conr,gvrcd100 to L>e determiaed by diverr,on model sz'vdy ort.-r len3th or ;900/ is set.
N0TC
Stations and elevations re,er t'o tur1ne,/ "'z.
ALWAYS nunK SAfETV UNITED STATES
DEPARTMENT OF T/wfE INTERIOR BUREAU OF RECLA'MATION
TCCHNIC,4L ASS!S,ANC.C PROGR/IM Ft::7RT46E /\trT/V, D.EVEL. .,_ PEACE /f/VEK _._ LJ.C. C;f/V.
PORTAGE MOUNTAIN DAM OUTLET WORKS
fa100£L STUDY - SCh'£M£ H
DRAWN . • /?._...(.._ £:.. .SUBM1TrEtJ . •. ________ _
TRACE:0 .•. ••.•.•.••..• .• RE:COMMENDED-- ---- - - • - --- -·· --
Ct-f~~D- • .•• _ .•. __ ____ APPROV6.D ••. ••• ----- •. __ ••• _. _ •• __ --· --
r
;62,~00E
Rock bolts
, S•.()095/
Gate installations and details not .shown---
os req'tt ------
I I
/-/ I I
SECTION A-A
---£/. 16.16:00
I I
~--Sta. l7•68S7
PLAN 0 100 zoo
SCALE 01"" FEET
/--Original gravnd surlace
\ S•.OO!J~_,,,
L \steel /i,xr \-Sta. /2+78.57 >-A
1-SZ'O. 11.-.zo
PROFILE ON t. TUNNEL NO. 2
2./50 >------,--------,------,----,--;--,
Discharge pe.r tvnnel---20501----+---+-----t----
< ~ r ,~so f-_ ___ 1----1------+---++---+----1 I..J ij
~ ~ 1850
~ VJ
~ /750
1650 0 2 4 6 8 m /2 OISCf/AR6£ IN TH0I/SANDS OF CF. .5.
I \
APPENDIX FIGURE 9 REPORT HYO-
1900
/BOO
-+,60~0"f,<- '-Air vent s-,,stem Portal luce, ~ No. I, Sta. 1~67.00 --- _ _- I
1600
No.2 sto. N-87.00 --:;;-,,..-No.i Sta. 1+97.0o--
heV. 3-9-65 Plug deDJils, stilling bas,n, st,d/on A-A, zt71lwater and discha,ye cvrves added_
ALIIIAYS n11n11 SAHTY VNITEO STATES
OE,-AlfTMENT Otr THE INTElflOlf 8VlfEAV Otr lfEC~AflltlATION
T=HNICAL ;;fSSISTAHCC PROdll'AH E'Off!TAG£ MTN. D£VEL - PEACE RIVER - [J.c, C"IN.
PORTAGE: MOtlNTAIN DAM OClrLET WOHKS GENERAL PLAN
OlfAWN. R~,:: ___________ SV8MITRO .•..••.•..•.••.• --.-- .. ·····----··
TRACEO-. ___ -- ••• - -·---AECOlltlMEN~O- -- -·- -·- - ----·-· ··- •·- -··--
CHECKEQ_,;_IJtll/_ ______ ----~_,,,OVEO--- - --- - ---- -·- --· - • ·---· --· •-
N/IIVERC0L0. lJEC.21964
5,000 cfs, Reservoir El. 2100
Flow at upstream end of tunnel
10, 100 cfs, Reservoir El. 2100
Flow at downstream tunnel portal
PORTAGE MOUNTAIN DAM OUTLET WORKS
STILLING BASIN OPERATION WITH BOTH GATES DISCHARGING 1:24 SCALE MODEL
7-1750 (lo-64)
CONVERSION FACTORS-BRITISH TO METRIC UNITS OF MEASURJ!MENT
The tollowing conversion £actors adopted b,y the Bureau or Reclamation are those published b,y the .American Societ.y ror TestiDg and l,laterials (.ASTM Metric Practice Guide, January- 1964) except that additional £actors (*) c~ used in the Bureau have been added. Further discussion or definitions or quantities and units is given on pages 10-11 or the ASTM Metric Practice Guide.
The metric units and conversion £actors adopted b,y the AS'D4 are based on the "International B,ystem or Units" (designated SI tor B,ysteme International d'Unites), tilted b,y the International Committee tor Weights and Measures; this system is also knOlln as the Giorgi or MllBA (meter-kilogram (mass)-second-ampere) system. This system has been adopted b,y the International Organization tor standardization in ISO Recanmendation R-Jl.
The metric technical unit or rorce is the kilogram-torce; this is the rorce which, when applied to ab~ haviIJg a mass or l kg, gives it an acceleration or 9.80665 m/sec/sec, the standard acceleration or tree £all toward the earth's center tor sea level at 4' deg latitude. The metric unit or rorce in SI units is the newton (N), which is defined as that rorce which, when applied to ab~ having a mass or l kg, gives it an acceleration or l m/sec/sec. These units must be distinguished tram the (inconstant) local weight or a~ having a mass or l kg; that is, the weight or a ~ is that rorce with which ab~ is attracted to the !ISl'th and is equal to the mass or a~ multiplied b,y the acceleration due to gravit.y. However, because it is general practice to use "pound" rather than the technic~ correct term "pound-torce, 11 the term "kilogram" (or derived mass unit) has been used in this guide instead or 11kilogramrorce11 in expressiIJg the conversion £actors tar rorces. The newton unit or rorce will find increasiIJg use, and is essential in SI units.
Mil. Inches
Feet.
Jmltip]y
Yards •••••• Miles ( statute) .
Square inches. Square reet.
Square yards Acres ••••
Square ml.lea
Cubic inches Cubic reet • Cubic yards.
Fluid OIJIICeS (U.S.)
Liquid pints (U.S.)
Quarts (u .s.).
Gallons (U.S.)
Qallons (U.K.)
Cubic reet • Cubic yards Acre-reet.
Table l
QIJANl'ITIF.S AND 1INITS OF SPACE
LENGTH
25 • 4 (exact~) • 25.4 (exact~). , 2.54 (exac~)*
30.48 (exac~) , .• 0,3048 (exac~)* •• O .0003048 (exact~)* • 0.9144 (exac~) •
1,609.3" (exact~)* • 1.609344 (exactly)
AREA
6,4'16 (exact~) 929.o:J (exact~)* ••
0.092903 (exact~) 0.836127 •• 0.40469'S ••
4,046.9* •••• 0.0040469*. 2.58999 ••
16.3871 ••• 0.0283168 • 0.'764SS5.
CAPACITY
29.'777, • 29.5729 •• 0.473179. 0.473166.
9,463.58 ••• 0,946358,
3,785,43* •• 3,78543 • 3.78533 ••• 0,00378543* , 4,54609 4.54596
28.3160. '764.55*
•, 1,233,5* • 1.233,500*
To obtain
• Micron • Ml.lllmeters • Centimeters • Centimeters • Jl!ters • Kil01119ters • Jl!ters • Milters • Kilometers
• Square centimeters , Square centimeters • Square meters • Square meters • Hectares • Square meters • Square kf.loaetsrs • Square kilometers
• Cubic centimeters • Cubic meters • Cubic meters
• Cubic centimeters • 111.11111 ters • Cubic decimeters • Liters • Cubic centimeters • Liters • Cubic centimeters • Cubic decimeters • Liters • Cubic meters • Cubic decimeters • Liters • Liters • Liters • Cubic meters • Liters
Mll.tiply
Grains (1/7,000 lb) , , , Troy ounces ( 480 grains). OUnoes (avdp) , • , , Pounds (avdp) , , , , Short tans (2,000 lb)
Lang tans (2,240 lb)
Pounds per square inch
Pounds per square foot
Quncee per cubic inch • , , Pounds per cubic foot , • •
Tans (1.cmg) per cubic yard'
OUnoes per gallcm ( U ,S , ) , Ounces per gallcm (U.K,}. Pounds per gallcm ( U ,S. ) , Pounds per gallcm (U.K,),
Inch-pounds
Foot-pounds
Foot-pounds per inch OUnoe-inches ,
Feet per second
Feet per ;year , Miles per hour
Feet per second2
MASS
64. 79891 (exactly) • )1.1035 •••••• 28,3495 • , •• , •• 0 ,45359237 {exactly)
907,185 • , , , • 0,907185 , , • ,1,016.05 , , , , ,
FORCE/AREA
0,070307 0,689476 4,88243
47,880) •
MASS/VOLUME (DENSITY)
1.72999 • 16,0185 , , ·0,0160185 1,32894, •
MASS/CAPACITY
7,4893 6.2362
119.829 99.779
BENDING IO.lENT OR TORQUE
~:~:~\'i66' 0,1)8255 , , , 1,)5582 X 107 5,4431 ••• ,
72.008 ••••
VELOCITY 30,48 (exactly} , , 0.3048 (exactly)* 0,965873 X 10-tlot , l.609~ {exaci1:7) 0.44701. (exact~
ACCELERATION* 0.'.1048*. • •
FWII Cubic feet per second ( second-
feet) , , , , , , , , , • , , 0,028317*, 0,4719 •• 0.06309 ,
Cubic feet per m1nute , , Oallans (U,S,) per ml.nute
~
QUANTITIES AND UNITS OF MECHANICS
To obtain
• Milligrams • Orama • Grams • Kilograms • Kilograms • Metric tans • Kilograms
, Kilograms ;-er square centimeter , Newtons per square centimeter , Kilograms per square meter • Newtans per square moter
, Orems per cubic centimeter , Kilograms per cubic moter , Ormaa per cubic centimeter
Orama per cubic centimeter
• Grams per liter • Orama per liter • Grams per liter • Grams per liter
• Meter-kilograi,a , Centimeter-dynes , Meter-kilograms , Centimeter-dynes , Centimeter-kilograms per centimeter 1 Oram-centimeters
, Centimeters per second , Meters per second , Centimeters per seocmd , Kilometers per hour , Meters per second
, Meters per seoond2
, CUllic meters per second , Liters per second , Liters per second
Multiply By
Pounds 0 ,45)592* • • • 4,44112* •••• 4,4482 X 10•5* •
YfOBK ANP MBGX*
British thermal uni ts ( Btu) ,
Btu per pound,
, 0,252* • , , •• • 1,055.06 , ••• , ,
2.326 (exactly), 1,35582* ••• Foot-pound&,
Horsepower • • , , • , Btu per hour • , , • , Foot-pounds per second
Btu in,/br rt2 deg F (k, thel"IIBl conducti vi t;y)
Btu f't/br tt2 deg F .. : :
Bt~:, ~ ~C~ ~:~ Deg F hr rt2/Bt.; (R; th;~
resistenoe) , , , , . . . . . Btu/lb deg F {c, heat capacity}, Btu/J.b deg F , , , , , , , • • , Ft2/br ( thermal dii'f'usi vi ty)
Grains/hr ft2 ( water vapor transml.ssion), , • • , •
Perms ( permeence) , , • , • Perm-inches (permeability)
Cubic feet per square foot per de;y {seepage) • • . . . . .
Pound-seconds per square foot (viscosity). , • , • • • • • • •
Square feet per second ( visoosi ty) FahreDbe:l:t degrees (change)* , Volts per ml.l, ••• , •• , , Lumen& per square foot ( foot-
candles) Ohm-circular ml.ls per foot Millicuries per cubic foot Milliamps per square toot Gallans per square ;yard Pounds per inch,
POWER
745,700, , •• 0,293071 , •• 1.35582 •••
HEAT TRANSFER
1,442 • 0,1240 , 1,4880*
0,568 4,882
1.761 4,1868 1,000* 0,2581 , 0,09290*
WATER VAPOR TRANSMISSION
16,7 • 0,659 1,67
!!!!!!..1ll OTHER QUANTITIES AND UNITS
304,8*
4,8824* , , , , , 0,02903* {exactly) 5/9 exactly. 0.03937.
10.764 • 0,001662
35,)147* 10,76)9*
4,527219* 0,17858* •
To obtain
Kilograms Newtons Dynes
• Kilogram calories • Joules • JOlles per gram • Joules
• Watts , Watts • Watts
• Milliwatts/cm deg C , Kg cal/br m deg C • Kg cal m/br m2 deg C
. Milliwatts/cm2 deg C • Kg cal/hr m2 deg C
. Deg C cm2/ml.lliwatt • J/g deg C , Cal/gram deg C • cTJil./sec • !R-/hr
, Orams/24 hr TJil. , Metric perms • Metric perm-centimeters
To obtain
• Liters per square meter per d~
• Kilogram second per square meter • Square meters per second , Celsius or Kelvin degrees (change}* • Kilovolts per ml.llimeter
• Lumens per square meter • Ohm-square ml.llimeters per meter • Millicuries per cubic meter , M:1.lliamps per square meter • Liters per square meter • Kilograms per centimeter
GPO 845-237
ABSTRACT
Studies on a 1:14 scale model of the low 'level outlet works of Portage Mountain Development show the fixed-cone valve-ring deflector combination provides a relatively simple and effective device for flow control and energy dissipation. The ring deflector contributes significantly to energy dissipation. Baffle piers downstream from the deflector and a weir at the downstream tunnel portal can be added later to improve energy dissipation if necessary. The extent of the steel-lined section required downstream of the valves was determined. High fluctuating pressures were measured on the wall of the liner in the impingement area of the jet and on the upstream face of the ring deflector at the crown and invert. Pressures on the lip of the deflector were slightly subatmospheric. No uniform simultaneous peaking of pressures at widely separated areas occurred on the deflector ring. A recirculating air supply tunnel was developed to provide near atmospheric pressures within the cone-shaped jet as well as upstream of the jet at the valves. Nonsymmetrical operation of the valves is not recommended. The design discharge of 10, 000 cfs per tunnel at reservoir elevation 2125 was verified by the model operation.
ABSTRACT
Studies on a 1:14 scale model of the low 'level outlet works of Portage Mountain Development show the fixed-cone valve-ring deflector combination provides a relatively simple and effective device for flow control and energy dissipation. The ring deflector contributes significantly to energy dissipation. Baffle piers downstream from the deflector and a weir at the downstream tunnel portal can be added later to improve energy dissipation if necessary. The extent of the steel-lined section required downstream of the valves was determined. High fluctuating pressures were measured on the wall of the liner in the impingement area of the jet and on the upstream face of the ring deflector at the crown and invert. Pressures on the lip of the deflector were slightly subatmospheric. No uniform simultaneous peaking of pressures at widely separated areas occurred on the deflector ring. A recirculating air supply tunnel was developed to provide near atmospheric pressures within the cone-shaped jet as well as upstream of the jet at the valves. Nonsymmetrical operation of the valves is not recommended. The design discharge of 10, 000 cfs per tunnel at reservoir elevation 2125 was verified by the model operation.
ABSTRACT
Studies on a 1:14 scale model of the low ·1evel outlet works of Portage Mountain Development show the fixed-cone valve-ring deflector combination provides a relatively simple and effective device for flow control and energy dissipation. The ring deflector contributes significantly to energy dissipation. Baffle piers downstream from the deflector and a weir at the downstream tunnel portal can be added later to improve energy dissipation if necessary. The extent of the steel-lined section required downstream of the valves was determined. High fluctuating pressures were measured on the wall of the liner in the impingement area of the jet ;µ-id on the upstream face of the ring deflector at the crown and invert. Pressures on the lip of the deflector were slightly subatmospheric. No uniform simultaneous peaking of pressures at widely separated areas occurred on the deflector ring. A recirculating air supply tunnel was developed to provide near atmospheric pressures within the cone-shaped jet as well as upstream of the jet at the valves. Nonsymmetrical operation of the valves is not recommended. The design discharge of 10, 000 cfs per tunnel at reservoir elevation 2125 was verified by the model operation.
ABSTRACT
Studies on a 1:14 scale model of the low level outlet works of Portage Mountain Development show the fixed-cone valve-ring deflector combination provides a relatively simple and effective device for flow corttrol and energy dissipation. The ring deflector contributes significantly to energy dissipation. Baffle piers downstream from the deflector and a weir at the downstream tunnel portal can be added later to improve energy dissipation if necessary. The extent of the steel-lined section required downstream of the valves was determined. High fluctuating pressures were measured on the wall of the liner in the impingement area of the jet and on the upstream face of the ring deflector at the crown and invert. Pressures on the lip of the deflector were slightly subatmospheric. No uniform simultaneous pea.king of pressures at widely separated areas occurred on the deflector ring. A recirculating air supply tunnel was developed to provide near atmospheric pressures within the cone-shaped jet as well as upstream of the jet at the valves. Nonsymmetrical operation of the valves is not recommended. The design discharge of 10, 000 cfs per tunnel at reservoir elevation 2125 was verified by the model operation.
Hyd-562 Beichley, G. L. HYDRAULIC MODEL STUDIES OF PORTAGE MOUNTAIN DEVELOPMENT LOW-LEVEL OUTLET WORKS--BRITISH COLUMBIA, CANADA USBR Lab Rept Hyd-562, Hyd Br, Jwie 30, 1966. Bureau of Reclamation, Denver, 80 p, 1 tab, 52 fig, 5 ref, append
DESCRIPTORS-- *outlet works/ diversion tunnels/ conduits/ twinel plugs/ hydraulic structures/ *hydraulic models/ hydraulic jumps/ stilling basins/ *air demand/ head losses/ discharge measurement/ energy losses/ backwater profiles/ steel linings/ weir crests/ baffles/ vapor pressures/ cavitation/ *energy dissipation/ water surface/ erosion/ tunnel linings/ oscillographs/ transducers/ laboratory tests IDENTIFIERS-- *Jet flow gates/ tunnel transitions/ fixed-cone valves/ ring de:fl.ectors/ subatmospheric pressures/ Portaqe Mtn Dvlpmt, Can/ bell-mouthed entrances/ British Columbia, Canada
Hyd-562 Beichley, G. L. HYDRAULIC MODEL STUDIES OF PORTAGE MOUNTAIN DEVELOPMENT LOW-LEVEL OUTLET WORKS--BRITISH COLUMBIA, CANADA USBR Lab Rept Hyd-562, Hyd Br, Jwie 30, 1966. Bureau of Reclamation, Denver, 80 P;: 1 tab, 52 fig, 5 ref, append
DESCRIPTORS-- *outlet works/ diversion tunnels/ conduits/ twinel plugs/ hydraulic structures/ *hydraulic models/ hydraulic jumps/ stilling basins/ *air demand/ head losses/ discharge measurement/ energy losses/ backwater profiles/ steel linings/ weir crests/ baffles/ vapor pressures/ cavitation/ *energy dissipation/ water surface/ erosion/ tunnel linings/ oscillographs/ transducers/ laboratory tests IDENTIFIERS-- *jet flow gates/ tunnel transitions/ fixed-cone valves/ ring de:fl.ectors/ subatmospheric pressures/ _Portage Mtn Dvlpmt, Can/ bell-mouthed entrances/ British Columbia, Canada
I I I I I I I I I I I I I I I I I ! I I I I I I
Hyd-562 Beichley, G. L. HYDRAULIC MODEL STUDIES OF PORTAGE MOUNTAIN DEVELOPMENT LOW-LEVEL OUTLET WORKS--BRITISH COLUMBIA, CANADA USBR Lab Rept Hyd-562, Hyd Br, Jwie 30, 1966. Bureau of Reclamation, Denver, 80 P,: 1 tab, 52 fig, 5 ref, append
DESCRIPTORS-- *outlet works/ diversion tunnels/ conduits/ twine! plugs/ hydraulic structures/ *hydraulic models/ hydraulic jumps/ stilling basins/ *air demand/ head losses/ discharge measurement/ energy losses/ backwater profiles/ steel linings/ weir crests/ baffles/ vapor pressures/ cavitation/ *energy dissipation/ water surface/ erosion/ tunnel linings/ oscillographs/ transducers/ laboratory tests IDENTIFIERS-- *jet flow gates/ tunnel transitions/ fixed-cone valves/ ring deflectors/ subatmospheric pressl_ll'es/ Portage Mtn Dvlpmt, Can/ bell-mouthed entrances/ British Columbia, Canad.a
Hyd-562 Beichley, G. L. HYDRAULIC MODEL STUDIES OF PORTAGE MOUNTAIN DEVELOPMENT LOW-LEVEL OUTLET WORKS--BRITISH COLUMBIA, CANADA USBR Lab Rept Hyd-562, Hyd Br, Jwie 30, 1966. Bureau of Reclamation, Denver, 80 p, J tab, 52 fig, 5 ref, append
~
DESCRIPTORS-- *outlet works/ diversion tunnels/ conduits/ twine! plugs/ hydraulic structures/ *hydraulic models/ hydraulic jumps/ stilling basins/ *air demand/ head losses/ discharge measurement/ energy losses/ backwater profiles/ steel linings/ weir crests/ baffles/ vapor pressures/ cavitation/ *energy dissipation/ water surface/ erosion/ tunnel linings/ oscillographs/ transducers/ laboratory tests IDENTIFIERS-- *jet flow gates/ tunnel transitions/ fixed-cone valves/ ring deflectors/ subatmospheric presslll'es/ _portage Mtn Dvlpmt, Can/ bell-mouthed entrances/ British Columbia, -Canada
